Rules

Compendium of Rules for Wei-Qi (Go, Baduk)
Detailed rulesets from various sources. Also an interesting note on the mathematical consequences of various rulesets, and the 'beasts' that arise.
http://www.cs.cmu.edu/afs/cs.cmu.edu/Web/People/wjh/go/rules/

Go (Weiqi, Baduk) Rules
Includes discussion and resource on the rules of go and their variations.
http://home.snafu.de/jasiek/rules.html