Guitar

https://en.wikipedia.org/wiki/Guitar

Ultimate
http://www.ultimate-guitar.com/

Basics
http://www.guitarbasics.com/

Tab

http://www.guitaretab.com/

Center
http://www.guitarcenter.com/

Teach
http://www.teachguitar.com/

World
http://www.guitarworld.com/

Tube
https://www.youtube.com/results?search_query=guitar

Slides
http://www.slideshare.net/search/slideshow?searchfrom=header&q=guitar