There are hundreds of guitar sites out there. Some good ones and some 'not so good'. This is just a few sites for getting tab that google often doesn't reveal in the first few pages:
http://acousticpower.com A site with 100's of free PowerTab files
http://www.freetabs.org/listtabs.htm Lots of tabs ... mostly tef files.
http://www.acousticfingerstyle.com/midifils.htm Some interesting tab from a variety of artists
http://www.hotclub.co.uk/ptab/powertab.html Lots of jazz tunes in powertab format
http://www.willflyguitar.com/tablatures.html Tab arrangements by Will Fly
http://justinguitar.com Of the instructional sites I think this is one of the best.
http://www.tallstrom.com Martin Tallstrom ... many playing styles
http://www.boegershausen.de Ulli Bögershausen ... fine player and free tabs