Great Guitar Sites on the Web: http://www.vicnet.net.au/~guitar
Links to many guitar related sites.

 Bruce Arnold:
http://www.arnoldjazz.com
Bruce offers several books on various topics.

 OAGL Online Archive of Guitar Links: http://www.oagl.co
Links to guitar related items including instruction books.

 Guitar.net Internet Directory: http://www.guitar.net
A directory for instruction books as well as other guitar related stuff.

 Guitar College:
http://www.guitarcollege.com
A home study course.

Harmony Central:
http://www.harmony-central.com
A large music resource site containing everything related to the guitar that you can think of, and everything else.

Phil Forbes:
www.philforbes.com
Phil has a book on chords for 7-string guitar, CD and more.