Froogle:
Developed by Google, Inc. One of the most promising price comparison sites to date.
BizRate:
One of the largest price search sites. Over 30 million products listed.
Shopping.com:
Child of Dealtime and Epinions, now merged to provide you with three shopping search engines that feature your products separately, yet the same.
Yahoo Shopping:
Complete Yahoo Shopping data feed creation and maintenance solutions.
MSN Shopping:
Complete MSN Shopping data feed creation and maintenance solutions.
NexTag Shopping:
Complete NexTag data feed creation and maintenance solutions.
PriceGrabber Shopping:
Complete PriceGrabber data feed creation and maintenance solutions.
Used Book Trader
Used and out of print books; registration required.
Usedbooks Freeshipping
Used books in categories, plus records and eight-track tapes. Freeshipping promise does not apply outside USA.
Wyvern Books
Offering antiquarian and secondhand books for sale covering a varied range of interests. Many first editions, and hardbacks, with dustjackets.