Exhibit 10.31

FOURTH ADDENDUM TO

ADCENTER LICENSE, HOSTING AND SUPPORT AGREEMENT

This Addendum is entered into between IAC Search & Media, a Delaware corporation
(“Partner”) and LookSmart, Ltd., a Delaware corporation (“LookSmart”) and is the
fourth addendum to that certain AdCenter License, Hosting and Support Agreement
by and between Partner and LookSmart entered into as of May 16, 2005, as amended
by the parties in three addenda effective January 2006, May 2006, and January
2007, respectively (the “Agreement”).

This Fourth Addendum is effective as of June 11, 2007.

Whereas, LookSmart has developed additional functionality to its AdCenter to
enable the serving of advertisements in response to the content of viewed web
pages (“Contextual Ad Serving”); and

Whereas, pursuant to Section 5(c) of the Agreement, LookSmart wishes to provide
this Contextual Ad Serving functionality to Partner;

Therefore, Partner and LookSmart agree as follows:

1. Delivery: LookSmart agrees that it will make Contextual Ad Serving available
to Partner on June 11, 2007.

2. Service Levels: The Service Level Agreement attached to the Agreement as
Exhibit A will apply to Contextual Ad Serving, except when the AdCenter is
required to retrieve content from Partner Network in order to have a copy or
refresh a copy of the content.

3. Contextual Ad Serving Metrics: LookSmart will develop a system for measuring
latency for those contextual ad calls that require LookSmart to retrieve content
from Partner Network in order to have a copy or refresh a copy of the content
(excluding the time required for LookSmart to retrieve the content from Partner
Network) (the “Contextual Ad Serving Metrics”) by August 1, 2007. The Contextual
Ad Serving Metrics will not be subject to the existing Service Level Agreement.

4. Except as modified herein, the Agreement shall remain in full force and
effect.

 

Partner     LookSmart, Ltd. By:  

/s/ Dominic Butera

    By:  

/s/ Michael Schoen

Name:  

Dominic Butera

    Name:  

Michael Schoen

Title:  

Chief Financial Officer

    Title:  

Vice President, Product and Technology