"ShopWiki actively crawls more than 180,000 online stores to ensure you’ll find the products you want at the best prices." For a class looking at web2.0 apps, it's the kind of thing students would enjoy playing with.
how to refine a topic and its searches; updated for web 2.0 and specialty searching; good for anyone starting to do Internet research on a topic and will take you to some previously unused search tools
social bookmarking portal lets users share expertise on some subject; room for author's comments and explanations; more discursive than delicious; less writing than a blog; see "Visual Thinking," also "Ephemeral Films"
The invisible web, or deep web, is estimated to be 500 times bigger than the searchable web and comprises databases and results of specialty search engines that the popular search engines can't index.