Jan Prokop (of Waltheri's go pattern search fame) created a growing GitHub repository: List of go libraries.
Quote from there:
waltheri wrote:
The idea of this repository is to collect cool libraries, tools and applications for game of go, which could be used by developers. It is primarily intended for web developers, but all projects are welcome. There are only 2 rules: code of the project must be licensed as open source (so other people could use it) and it must be in some public web repository (if a library doesn't have GitHub, it isn't cool 
).
).