FORM OF EXCHANGE AGREEMENT

Exhibit 10.1

FORM OF EXCHANGE AGREEMENT

        THIS EXCHANGE AGREEMENT, dated as of August [    ], 2005 (the "Agreement"), is by and between ValueClick, Inc., a Delaware corporation ("Parent"), and [    ] (the "Stockholder"), a [    ] and a stockholder of Fastclick, Inc., a Delaware corporation (the "Company"). Terms used but not otherwise defined in this Agreement shall have the meanings ascribed to such terms in the Merger Agreement (as defined below).

RECITALS

        WHEREAS, contemporaneously with the execution and delivery of this Agreement, Parent, Acquisition and the Company are entering into an Agreement and Plan of Merger and Reorganization, dated as of the date hereof (the "Merger Agreement"), which provides for (a) the Offer by Parent to purchase all of the outstanding Shares of the Company and (b) the merger of Acquisition with and into the Company (the "Merger").

        WHEREAS, as of the date hereof, the Stockholder owns (beneficially and of record) an aggregate of [    ] Shares (all Shares so owned and which may hereafter be acquired by the Stockholder prior to the termination of this Agreement, whether by means of purchase, dividend, distribution or otherwise, being referred to herein as the "Owned Shares");

        WHEREAS, as a condition to its willingness to enter into the Merger Agreement, Parent has required that the Stockholder enter into this Agreement; and

        WHEREAS, in order to induce Parent to enter into the Merger Agreement, the Stockholder is willing to enter into this Agreement; and

        WHEREAS, for U.S. federal income tax purposes it is intended that this Agreement be treated as part of the transaction that includes the Offer and the Merger, and that such transactions together qualify as a reorganization under the provisions of Section 368(a) of the Internal Revenue Code of 1986, as amended (the "Code"), and the regulations promulgated thereunder, and that this Agreement constitute part of the "plan of reorganization" for purposes of Sections 354 and 361 of the Code.

AGREEMENT

        NOW, THEREFORE, in consideration of the foregoing and the mutual covenants and agreements herein contained, and intending to be legally bound hereby, Parent and the Stockholder hereby agree as follows:

ARTICLE 1

COVENANTS OF THE STOCKHOLDER

        Section 1.1.    Tender of Shares.    In no event later than two (2) business days prior to the Initial Expiration Date or, if the Offer is extended, two (2) business days prior to the Expiration Date, the Stockholder shall tender (or cause to be tendered) all of the Owned Shares in exchange for shares of Parent Common Stock pursuant to and in accordance with the Offer, and shall not withdraw or revoke such tender (or cause such tender to be withdrawn or revoked), except in the event that this Agreement has been terminated in accordance with Section 4.2 below. Notwithstanding the foregoing, this Section 1.1 will be of no force and effect and shall not constitute a binding covenant or agreement of the Stockholder to the extent that, but only for so long as, this Section 1.1 or the Stockholder's performance of this Section 1.1 would result in a violation or breach of, or constitute (with or without due notice or lapse of time or both) a default under, the Public Offering Lock-Up Agreement (as defined herein); it being understood that, at such time that this Section 1.1 ceases to result in a violation or breach of, or to constitute (with or without due notice or lapse of time or both) a default

under, the Public Offering Lock-Up Agreement, this Section 1.1 shall thereafter be a binding and enforceable covenant and agreement of the Stockholder.

        Section 1.2.    No Inconsistent Actions.    Except as contemplated by this Agreement and the Merger Agreement, the Stockholder shall not, during the term of this Agreement (a)(i) transfer (which term shall include, without limitation, any sale, assignment, gift, pledge, hypothecation or other disposition), or (ii) consent to any transfer of, any or all of the Owned Shares or any interest therein, or (iii) create or permit to exist any Lien on the Owned Shares, (b) enter into any contract, option or other agreement or understanding with respect to any transfer of any or all of the Owned Shares or any interest therein, (c) grant any proxy, power-of- attorney or other authorization in or with respect to the Owned Shares, (d) deposit the Owned Shares into a voting trust or enter into a voting agreement or arrangement with respect to the Owned Shares, (e) take any other action that would in any way restrict, limit or interfere with the transactions contemplated hereby or the Merger Agreement, or the performance of its obligations hereunder (f) object to, or otherwise commence or support any proceeding or material action to oppose, the Offer or take any action that is materially inconsistent with the covenants of the Stockholder included herein or would unreasonably delay the consummation of the Offer.

        Section 1.3.    Stop Transfer.    The Stockholder shall not request that the Company register the transfer (book-entry or otherwise) of any certificate or uncertificated interest representing any of the Owned Shares, unless such transfer is made in compliance with this Agreement.

        Section 1.4    Disclosure.    The Stockholder agrees that it shall not make any announcement of disclosure regarding this Agreement or the transactions contemplated hereby without the prior written consent of Parent, except disclosures required by law or judicial order.

        Section 1.5.    No Solicitation.    During the Term, the Stockholder shall not, nor shall it permit or authorize any of its affiliates, officers, directors, employees, agents or representatives (collectively, the "Representatives") to, (a) solicit, initiate or encourage, directly or indirectly, any inquiries regarding, or the submission of, any proposal for a Third Party Acquisition or (b) enter into any agreement with respect to any proposal for a Third Party Acquisition or approve or resolve to approve any proposal for a Third Party Acquisition; provided, however, that nothing herein shall prevent the Stockholder from complying with its obligations under Section 13(d) of the Exchange Act. Upon execution of this Agreement, the Stockholder shall, and it shall cause each of its Representatives to, immediately cease any existing activities, discussions or negotiations with any parties with respect to any of the foregoing. The Stockholder shall promptly notify Parent in the event it receives any proposal or inquiry concerning a Third Party Acquisition, including the terms and conditions thereof and the identity of the party submitting such proposal, and the Stockholder shall advise Parent from time to time of the status and any material developments concerning the same.

        Section 1.6.    Capacity as Stockholder.    The Stockholder signs this Agreement solely in the Stockholder's capacity as a stockholder of the Company, and not in the Stockholder's capacity as a director, officer or employee of the Company or any of its Subsidiaries. Notwithstanding anything in this Agreement to the contrary, nothing in this Agreement shall in any way restrict a director, officer or both of the Company in the exercise of his or her fiduciary duties consistent with the terms of the Merger Agreement as a director of the Company or prevent or be construed to create any obligation on the part of any director, officer of both of the Company from taking any action in his or her capacity as a director or officer of the Company.

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ARTICLE 2.

REPRESENTATIONS AND WARRANTIES OF THE STOCKHOLDER

        The Stockholder hereby represents and warrants to Parent as follows:

        Section 2.1.    Organization; Authority Relative to this Agreement.    The Stockholder has all requisite power and authority to own, lease and operate its properties and to carry on its business as now being conducted. The Stockholder has all necessary power and authority to execute and deliver this Agreement and to perform its obligations under this Agreement, including, without limitation, the tender of the Owned Shares in the Offer. The execution, delivery and performance of this Agreement have been duly and validly authorized by all necessary action on the part of the Stockholder, and no other actions on the part of the Stockholder are necessary to authorize this Agreement or to perform the Stockholder's obligations hereunder. This Agreement has been duly and validly executed and delivered by the Stockholder and, assuming the due authorization, execution and delivery hereof by Parent, constitutes a valid, legal and binding agreement of the Stockholder, enforceable against the Stockholder in accordance with its terms, subject to any applicable bankruptcy, insolvency (including all applicable laws relating to fraudulent transfers), reorganization, moratorium or similar laws now or hereafter in effect relating to creditors' rights generally or to general principles of equity (regardless of whether enforcement is considered in a proceeding in equity or at law).

        Section 2.2.    Consents and Approvals; No Violations.    Except for filings, permits, authorizations, consents and approvals as may be required under applicable requirements of the Exchange Act and the HSR Act and any filings under similar merger notification laws or regulations of foreign Governmental Entities, no filing with or notice to and no permit, authorization, consent or approval of any Governmental Entity is necessary for the execution, delivery and performance by the Stockholder of this Agreement, except where the failure to obtain such consents, approvals, authorizations or permits, or to make such filings or notifications would not prevent or delay the performance by the Stockholder of the obligations to be performed by it under this Agreement.. Neither the execution, delivery and performance of this Agreement by the Stockholder nor the consummation by the Stockholder of the transactions contemplated hereby will (i) result in a violation or breach of or constitute (with or without due notice or lapse of time or both) a default (or give rise to any right of termination, amendment, cancellation or acceleration or Lien on the Owned Shares) under any of the terms, conditions or provisions of any note, bond, mortgage, indenture, contract, agreement, lease, license, permit, franchise or other instrument or obligation to which the Stockholder is a party or by which the Stockholder or its properties or assets are bound or (ii) violate any order, writ, injunction or decree to which the Stockholder is subject, or, subject to the receipt of the filings, permits, authorizations, consents and approvals referred to in the first sentence of this Section 2.2, any law, statute, rule or regulation applicable to the Stockholder or any of its properties or assets, except for violations, breaches or defaults that would not prevent or delay the performance by the Stockholder of the obligations to be performed by it under this Agreement.

        Section 2.3.    Title to Shares.    The Stockholder is the sole legal and record owner of the Owned Shares, free and clear of any pledge, lien, security interest, mortgage, trust, charge, claim, equity, option, proxy, voting restriction, voting trust or agreement, understanding, arrangement, right of first refusal, limitation on disposition, adverse claim of ownership or use or encumbrance of any kind ("Encumbrances"), other than Encumbrances imposed by the securities laws or pursuant to this Agreement, the Merger Agreement, or the Public Offering Lockup Agreement (as defined below), or Encumbrances that would not conflict with this Agreement or prohibit the Stockholder's performance of its obligations hereunder.

        Section 2.4.    Certain Commitments.    The Stockholder hereby represents that the Stockholder is not, and that from the date hereof through and including the Closing Date, neither the Stockholder nor any transferee of the Owned Shares shall become, subject to a binding commitment to sell, exchange or

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transfer by gift (or take any other action that would be treated for federal income tax purposes as a disposition of) any of the Offer Consideration to be received by it pursuant to the Offer.

        Section 2.5    Other.    The Stockholder has been represented by counsel in connection with this Agreement and the transactions contemplated hereby. The Stockholder has reviewed, or has had the opportunity to review, with the assistance of professional and legal advisors of its choosing, sufficient information necessary for the Stockholder to decide to tender the Owned Shares pursuant to the Offer.

        Section 2.6    Release From Public Offering Lockup Agreement.    The Stockholder has received any and all releases from the lock-up agreement by and among the Company, Credit Suisse First Boston LLC, Citigroup Global Markets Inc., Thomas Weisel Partners LLC and Jefferies Broadview, a division of Jeffer