To me, this is quite possibly one of the most perfect uses for a wiki. Tab sites have always been a bit clunky, dubiously organized, and increasingly filled with intrusive ads. They've always thrived on the work of a few, as writing tabs is not only time-consuming, but a lot of work in general. When you find a bad tab, most of the time you just don't have enough gumption to make corrections, send it in to a random webmaster, and hope that the changes are made, and so a wiki seems like a perfect solution. I stumbled upon this randomly while trying to find a good site for Iron and Wine tabs. It's still a small and fledgling outfit, but it looks like it's off to a good start, and so hopefully some exposure might give it a boost. I thought this would also be a good time to put out a call out for the favorite sites of any guitar/ukelele/mini-cymbals/grinder/any instrument playing monkeys out there. I would've liked to had more links to add, but the piano tab sites I used to go to are defunct now.
TabWiki! Yes, it's yet another wiki, but this time with more auto-didacticness!