Trolling through my drafts, I came across this site that was link to by Lifehacker. It was a page entitled: Massive Resource List for All Autodidacts. (Alas, secular education only, unfortunately. They left out my favorite place: Biblical Training.org.)
It looks like the link automatically redirects to a new page, and the new page doesn't seem to have the "massive" quality that the original had. However, thanks to the magic of the Internet Archive, you can still access the original.