When I was in a big rut, I started this site.
True story, I couldn't think of anything to play that wasn't plain vanilla pentatonic scale. I was hoping somebody would send me some cool riffs.

Lately, when I want something new I try magnus and johan for difficulty. I also like peter's stuff for originality. I also get a lot out of the acoustic stuff at www.guitarwar.com

I just got a really good jazz-slanted theory book. I am not into jazz, but wanted to brush up my theory education. It is called "Theory and Harmony for the Contemporary Musician" by Arnie Berle.

hope this helps.