Where do you buy knits and ribbing?

I'm working on a post for Monday of places I've found that sell ribbing, knits, and other fabrics you might want to use for a sweatshirt. I'd like to compile a great list we can all use in the future so this is where you come in. Tell me, is there somewhere you've found that has great ribbing or knits? Fill us in!! I'll be posting a complete list on Monday of where I've found them as well as any suggestions you guys have.