Lately we've seen some fun shopping mashups that aren't just simple price comparison apps. Instead these use the APIs--mostly Amazon Product Advertising API--to track your collections, keep up-to-date with entertainment and find products in a fun, conversational way.
iTrackmine.com: Are you the type of person who likes to be organized? Have you ever seen something cool and can't remember if you already own it? Then you'll love iTrackmine.com -- an aggregator of everything you own. APIs: Amazon S3, Bit.ly, Facebook, FriendFeed, Library of Congress SRW, RPX, Twitter. More at our iTrackmine.com profile.
TrackTVLinks: Search for online video and movies and display twitts and various info about the movie you're looking for APIs: Amazon eCommerce, Twitter, Yahoo BOSS. More at our TrackTVLinks profile.
SalesClark: An intelligent shopping assistant that communicates in plain English with online shoppers in order to quickly find the best and cheapest fit for their needs. APIs: Amazon eCommerce, Commission Junction, LinkShare. More at our SalesClark profile.