ArXiv - Free Research Papers - Open access to nearly a million scholarly papers published since 1991, with hundreds added every day. Subjects include physics, mathematics, computer science, quantitative biology, quantitative finance and statistics. The papers can be searched by author, title, and subject keywords. Hosted by the Cornell University Library.
Available anywhere through the Internet; registered users can submit their own articles. You will need to have Adobe Reader for the PDF files which can be downloaded or printed.