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EXHIBIT 10.18
 ADDENDUM TO
MASTER SERVICE AGREEMENT
 August 10, 2005
 ®  ®
   1.
    
    The following sentence shall be added to the end of Section 2.5(B)
(Cancellation and Termination Changes) of the MSA and shall read as
follows:

Upon Customers payment of the preceding fees and
fulfillment of Customers obligations under the Agreement, Customer
will no longer have an obligation to pay any additional termination
charges or make payment with respect to any remaining and unused portion of the Service Term.2.
    
    Article 3 (DEFAULT) of the Agreement shall be replaced with the
following:
 ARTICLE 3. DEFAULT
  3.
    
    The fourth sentence of Section 4.3 of the MSA (Services Levels)
shall be replaced with the following:
To request a credit, Customer
must contact Level 3 Customer Sevice (contact information can be
found at www.level3.com) or deliver a written request (with
sufficient detail necessary to identify the affected Service) within
60 days after the end of the month in which the credit was
earned;
however, should Customer terminate Service after delivery of the
Connection Notice pursuant to Section 2.5(B), Customer shall be
entitled to any Service Level credit not yet posted to Customers
account at the time of termination but incurred by Customer prior to
such termination provided Customer requests such credit in
accordance with this Section 4.3.4.
    
    Section 5.2 (Assignment and Resale) of the MSA shall be
replaced in its entirety with the following: 
5.2 Assignment and
Resale. Customer may not assign its rights or obligations under
this Agreement or any Customer Order without the prior written
consent of Level 3, which will not be unreasonably withheld. This
Agreement shall apply to any permitted transferees or assignees.
Notwithstanding the foregoing, Customer may assign its rights
hereunder to an entity controlling, or controlled by or under the
common control with Customer or to an entity that acquires
substantially all of the assets of Customer provided that the intended
assignee (A) agrees in writing to be bound by the terms of this
Agreement and (B) has the financial ability to meet the contractual
obligations of this Agreement. For purposes of the foregoing,
control shall mean the ownership of (i) greater than fifty percent
(50%) of the voting power to elect the directors of the company,
 or (ii) greater than fifty percent (50%) of the ownership interest in
the company. Customer may resell the Service to third parties,
provided that Customer shall indemnify, defend and hold Level 3
harmless from any claims made against Level 3 or its affiliates by
such third parties or any other parties or entities obtaining
service through such third parties. Nothing in this Agreement,
express or implied, is intended to or shall confer upon any thirty
party any right, benefit or remedy of any nature whatsoever under or by
reason of this Agreement.
 LEVEL 3 Communications, Inc. Confidential
    
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5.
    
    The following sentence shall be added to the end of Section 3 (Grant
of license) of the Colocation SS and shall read as
follows:
Level 3
represents and warrants to Customer that to the best of Level 3s
knowledge as of the Addendum Effective Date, (a) Level 3 has lease
rights at the property located at 8929 Aero Drive, San Diego, CA (the
Relevant Gateway); and, (b) Level 3 is not in default of its lease
in the Relevant Gateway.6.
    
    The following shall be added to the end of Section 4 (Use of
Colocation Space) of the Colocation SS and shall read as follows:
Customer shall not take any action that causes the
imposition of any lien or encumbrance on the Facilities and Level 3
shall not take any action that causes the imposition of any lien
or encumbrance on communications and networking equipment provided by
Customer.7.
    
    The first and second sentence of Section 10 of the Colocation SS
(Removal of Equipment) shall be replaced with the following:
Within 10 days following the expiration or termination of the Service
Term for any Colocation Space, Customer shall remove all Customer
equipment from the Colocation Space and Level 3 shall provide
Customer with reasonable access to the Colocation Space in order to
complete such removal. In the event Customer fails to remove the
equipment within such 10-day period, Level 3 may disconnect, remove
and dispose of Customers equipment without prior notice.8.
    
    The following new Section 10. Special Termination Rights Relative to
(3) CrossRoads®Service shall be added to the (3) CrossRoads SS and
read as follows:
 Special Termination Rights Relative to
(3) CrossRoads ® Service ® ® ® ®
 9.
    
    The terms and conditions set forth in this Addendum shall commence
on the Addendum Effective Date and continue for a minimum twenty four
(24) month period, unless terminated earlier by either party.10.
    
    Capitalized terms used but not defined herein shall have the
meanings
set forth in the Agreement.11.
    
    Except as amended hereby (and by any other addendum, if
applicable), all other
terms and conditions of the Agreement shall remain in full
force and effect.
 LEVEL 3 COMMUNICATIONS, LLC (Level 3)
    
    
    
    WEBSIDESTORY, INC. (Customer)By:
    
    /s/ Samantha B. Tumble
    
    
    
    By:
    
    /s/ TOM WILLARDSONName:
    
    Samantha B. Tumble
    
    
    
    Name:
    
    TOM WILLARDSONTitle:
    
    VP Legal
    
    
    
    Title:
    
    CFODate:
    
    
    
    
    
    Date
    
    9-22-05
 Level 3 Communications, Inc. Confidential
    
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