Adam Schneider's Guitar Files 
Chords and tablature for songs by varied artists. Includes guitar files, links and contact details.
http://adamschneider.net/music/Ultimate Guitar Archive
A sizeable archive of tabs. Also has a forum, lessons and reviews.
http://www.ultimate-guitar.com/
Xclusive Guitar Tabs
Diverse, small collection all tabbed by the site owner, Frederic Maquet.
http://www.geocities.com/SunsetStrip/3224/tabs.html
Tab Classics
A personal collection of the author's tabs, mostly of classic songs; includes a few arranged for acoustic fingerstyle guitar. Also offers a guide to using tablature.
http://homepage.ntlworld.com/rsls-phillips/tabclassics/
iTabs.nl
An archive of several thousand tabs, organized by artist, in a variety of genres; includes a number of non-English singing European artists.
http://www.itabs.nl/
Fretplay.com
A substantial collection of tabs for guitar (and some for bass), with discographies and CD reviews, and a forum.
http://www.fretplay.com/
Video Game Jam
Guitar tablature for video game music; also includes MIDI files.
http://videogamejam.com/
