I tried this before and failed miserably, but I figured I'd give it another go. I have more time to contribute to this now. Basically, I wanted to create a wiki site for guitar related information.

You can find it here:
http://guitarbook.ebonshadow.net/

When/if it starts to pick up, I'll buy a domain name for it. I really haven't added a whole lot to it yet but I will tonight. I have to go to work soon. If you feel like contributing, you can edit any page without even creating an account. Creating an account is free. This is basically a blank wikipedia. Eventually I plan to program some sort of syntax parser for tab, kind of like an html version of powertab. Until then, you can upload images exported from powertab and link to them.