In 2010, there are well-known collaborative Web sites for encyclopedic knowledge, photographic images, personal videos, and much else. Less well-known is a rich ecosystem of published datasets, including:

• "Some Datasets Available on the Web", with supplementary links here;
• "Datasets for Data Mining, Analytics and Knowledge Discovery";
• "A List of Social Tagging Datasets Made Available for Research"
• Linking Open Data on the Semantic Web: Datasets
• infochimps' "Find Any Dataset in the World"
• theinfo.org, "a site for large data sets and the people who love them ..."
• UCI Machine Learning Repository
• a Reddit thread on the subject of "Where can I find lists of data in useful computer formats? . . ."