BotSpot - Source for comparison of online shopping services.
Bottom Dollar -
CNET KillerApp - Listing of comparison shopping sites for electronics and computers.
Compare.Net - Huge listing of comparisons of items for the office and home, including appliances, computers, electronics and more.
Frictionless Commerce Incorporated - Offers comparison shopping for websites in a variety of categories.
Product ReviewNet - Product reviews in a variety of categories.
ValueShopper - Choose a category and pick your preferences and a comparitive list of merchants involved in this program will be displayed.