A definitive directory of worldwide OA repositories and their policies: ROARMAP
Check OPENDOAR also for academic OA repositories around the world.
See list of over 1500 repositories worldwide at Open Archives.
MELIBEA is an international directory listing both institutional repositories and their individual OA policies and requirements. It features a unique "estimator" that compares institutions with one another with respect to their "OA values" (their degree of openness with regard to publicly funded research).
Check out our Fulltext Sources Online directory (by subscription only)
The Social Science Research Network (SSRN) "is devoted to the rapid worldwide dissemination of social science research and is composed of a number of specialized research networks in each of the social sciences."
It includes both an abstracts database (over 345,000 items) and a collection of full text papers (280,000). SSRN Networks include free and fee-based journals in 13 subject areas ranging from accounting to rhetoric.