RePEc (Research Papers in Economics)
As their website puts it, "The heart of the project is a decentralized database of working papers, journal articles and software components. All RePEc material is freely available." There are more than 1,000 members; it is a rare for a major department or publisher to not participate. In all, RePEc contains information on more than 1,000,000 working papers and publications. More than 1,100 journals are covered, including those from North-Holland, Springer and the University of Chicago Press. RePEc is not designed for end-users, but IDEAS (Internet Documents in Economics Access Service) and EconPapers allows end-users to search the RePEc database, and New Economics Papers (NEP) distributes information on new entries in various fields via e-mail.
http://repec.org