Links related to improving your go playing strength.
A book on shape by Charles Matthews and Seong-June Kim.
Send one of your games to the Go teaching Ladder, and get a review by a stronger player! This is definitely a good way to improve. All the reviews from the past are available from this web site, too, so you could also play through some of them.
This is a huge SGF file with lots of joseki variations. The project was started by Gary Odom.
The journal of the French go association, including an archive of previous issues, a blog, and other resources around go in France
A large number of instructional videos on go (some require a subscription), and other resources.
Online database with pattern search engine
An online Joseki dictionary
An online joseki dictionary with an easy to use user interface.
Check your Go level. Test, created by Alexandr Dinershteyn, 3p
Move-by-move discussions on go games
Several pdf files with advice on playing handicap games.
All kind of resources (tsume go, game records, ...)