A good chunk of the links in this thread are dead, so I feel bad about linking people to this sticky when most of the links no longer work. Could someone either edit out the dead links or make a new thread with a list of working links? Seeing as how a lot of that stuff is from 2-3 years ago, I'm sure there are some new resources that can be linked instead.

Maybe this would be a good opportunity to expand the GDWiki?

Good idea -- I made a new thread. I put in some of the old links that still worked and eagerly await suggestions for more.