http://philsci-archive.pitt.edu/ A joint initiative by Philosophy Science Association and University of Pittsburgh, PhilSci Archive is an electronic archive for preprints in the philosophy of science. It is offered as a free service to the philosophy of science community with the goal to promote communication in the field by the rapid dissemination of new work.
At present the site contains more than 1800 records which can be browsed by year, subject or conferences/volumes.