RePEc – Research Papers in Economics. The archive consists of a network of databases from universities and research centers that deposit and make available their e-print collections.
SSRN – Social Science Research Network. The archive is dedicated to the dissemination of research in the fields of economics, finance, management, and marketing.
NBER Working Papers – Online collection of papers published by the National Bureau of Economic Research (US).
CEPR Discussion Papers – Online collection of papers published by the Centre for Economic Policy Research (UK)