The Social Science Research Network (SSRN) is a huge open-access repository for scholarly papers in law, the social sciences, business, and some other disciplines. Hundreds of thousands of authors have posted abstracts and papers. SSRN has over 750,000 abstracts—and most of the papers are available for free download (PDF).
It is a great tool for research (finding and getting access to papers), for disseminating information (authors sharing their papers), and for keeping up with new developments.