Not sure how many people remember this site, but it was made a year or two back and still has a ton of interesting PDF articles on it. I only bring it up because a good amount of the PDF's linked in the sticky either don't work or have been taken down, but while I don't think anyone's been on here since 2014 judging from the forums, it was an interesting idea that got off the ground but just didn't seem to take off. Thoughts?

http://thexlibrary.com/