For promoters to share where they are finding information or pictures from. I'll go first, with the easiest two.
[url=www. obsessedbywrestling.com]www. obsessedbywrestling.com[/url] has tons of photos and short bios on many wrestlers. They try to include such things as other identities, finishers and more.
www.ballparks.com can help you figure out what the major arenas in an area were. This comes in handy when trying to figure out what buildings were actually up and running 30 years ago. This won't help much if you are in an area with no major league sports, however.