http://www.silkqin.com/
This is the most extensive English website dedicated to the
qin, an absolute goldmine for its history, theory, literature, and more. It is the homepage of John Thompson, a true modern literatus and accomplished qin player renowned for his dedicated reconstructions of the earliest surviving qin repertoire.

http://www.cechinatrans.demon.co.uk/toc-qin.html
Most of what John Thompson doesn't cover can probably be found here, the other "indispensible"
qin page in English. Christopher Evans has unfortunately truncated his discography pages, which formerly included full track information. Rather ominously, the page entitled "Does the Guqin have a Future?" remains unwritten after many years!

http://www.tcfb.com/guqin/
A similar page from Peiyou Chang, with great explanations of fingering techniques.

http://members.aol.com/JMGJoseph/
The discography here is a recurring attraction.

http://en.wikipedia.org/wiki/Guqin
Charlie Huang has done the internet a great service with this wonderfully comprehensive article. The article on
qin schools was incidentally converted from a forum post by yours truly.

http://starvoid.proboards30.com/index.cgi?board=Guqin
On the topic of
guqin web-warrior Charlie Huang, here's the guqin section of his music forum, currently the only active qin forum in English.

Websites of regional
qin societies:
New York:
http://www.newyorkqin.org/
San Francisco:
http://www.guqin.com/
London:
http://www.ukchinesemusic.com/Londonyoulanqin/Frame_qinsoc.html

http://www.medieval.org/
One of the greatest music resources on the net, this is the stomping ground of musical mastermind and aesthetic philosopher Todd McComb. It contains enormous amounts of factual information relating to world music traditions and to early European music, plus an archive of music editorials whose concepts and arguments continue to inform my perspective. Todd was the one who first introduced me to the world of
qin, and is also one of the most vocal and articulate CM fans around.

And finally, the homepage of my dear
qin teacher, Shin-yi Yang:
http://www.shinyiyang.com/