Since anyone can publish a web site, carefully evaluate what is found (such as the organization creating/owning/hosting the site and the site authors). Here are a few information sites with which to get started.
Open-access to e-prints in Physics, Mathematics, Computer Science, and Quantitative Biology.
A highly-automated electronic archive and distribution server for research articles. Covered areas include physics, mathematics, computer science, nonlinear sciences, quantitative biology and statistics.