Inter-University Consortium for Political and Social Research - This organization has a large collection of data that have been formatted and contributed by many researchers. There are thousands of data files accessible to researchers. However, you must be affiliated with an organization that is a member to access the resources.
www.Quandl.com - This site provides a tremendous resource (5,000,000 datasets) which organizes the data from publicly available sites. They provide packages in R and Stata which allow you to in a single command access and download data files.
IPUMS - This organization assembles sampling of census years for the US and other countries. It is a vital resource for many research projects.
Economic Blog Aggregator
EconomicAcademics.org at the federal reserve is a blog aggregator that "looks through blog posts for a link to some research indexed on a RePEc service, currently EconPapers, IDEAS and NEP. IDEAS then also links back from the abstract page to the blog posts."
RePEc (Research Papers in Economics) is a collaborative effort of hundreds of volunteers in 75 countries to enhance the dissemination of research in Economics and related sciences.