The purpose of Data.gov is to increase public access to high value, machine readable datasets generated by the executive branch of the federal government.
narrative+history+pictures+encyclopedia; "safe, fast and fun way to learn the real story behind historic events, famous people, heroic exploits, legends, disasters, movies, plus topics of current and general interest"
"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.
many of the past issues were on thematic concerns; ever of greater importance in academic and knowledge communities is the how-to of electronic publishing
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.