Last week the free and open access repository for scientific (mainly physics but also math, computer sciences...) papers arXiv got past 500,000 different papers, not counting older versions of the same article. Especially for physicists, it is the number-one resource for the latest scientific results. Most researchers publish their papers on arXiv before they are published in a 'normal' journal. A famous example is Grisha Perelman, who published his award-winning paper exclusively on arXiv.