RePEc is about the facilitation of the diffusion of research in Economics. It does this through an open bibliography, which allows anyone to have its works listed, and anyone to use the bibliography. But of course, this is more powerful when the works are not just listed, but also available online with a direct link.
RePEc has now links to over a million works covering Economics and Finance, about half of which are in open access. While a majority are from journals (61%), online working papers are much more popular. While an article is download on average once every two months, working papers are downloaded close to once a month.