I spend far too much time looking around the web at guitar stuff so as I find interesting stuff, I am going to list it here. It's not for commercial gain, this is just great stuff I find around the place.

Lessons and guitar study

Tuck Andress
An awesome fingerstlye player, most famous for his "one man band" skills as part of Tuck and Patti. He has a whole heap of great information available on his site, really knowedgable guy, and a very clear thinker.

Info on Guitars, amps and effects

The Amp Guide (formally The Fender Field Guide)
My mate Dario told me about this site. If you are into old Fender amps, then you need to know this site!