Infochimps.org
http://infochimps.org/

Infochimps.org is a website where anyone can upload a dataset and make it a rich addition to the large library with good metadata tagging and descriptions. Much of the data will be free and come with an open license. Infochimps.org has thousands of datasets, including the Freebase data dump, Wikipedia extractions, stock data, and all sorts of text corpora. This will be added to Data Mining Resources Subject Tracer™. This has been added to Research Resources Subject Tracer™ Information Blog.