Check this site often!
I will be adding to the guitar resources quite a bit this year.

Articles and other resources:

Choosing a Guitar

Online Guitar Resources:

Music Theory Resources-

Music Theory.Net

http://www.practicespot.com/theorycenter.phtml?t=59

http://www.gmajormusictheory.org/index.html

http://teoria.com/

http://www.8notes.com/theory/

Other resources-

An online guitar tuner:    

http://www.8notes.com/guitar_tuner/

An online chord dictionary (will show and play the chord you want:
http://www.8notes.com/guitar_chord_chart/

An online metronome:
http://www.8notes.com/metronome/