A strong open source go engine, initiated and mainly developed by Petr Baudis
An open-source minimalistic Go Engine, based on Monte Carlo playouts, written in Python.
The algorithm is between 500 and 600 lines of code only. This is a great source for understanding how to apply Monte Carlo type algorithms to building a go playing program.
By Petr Baudis, the creator of Pachi.
Lots of information around computer go. Maintained by Nick Wedd.
The goal of the project is to investigate computer analysis of databases of Go game (Baduk, Weichi) records using computer data-mining algorithms. Includes a web app to analyze a player's style from a collection of her/his games.
From the site: "OpenGo is intended as a workbench for programmers interested in the challenges of writing automated Go opponents."
The go program Indigo. Links to other resources and projects.
A free, open-source, go-playing program.
Erik van der Werf's announcement to the computer go mailing list.
... maintained by Markus Enzenberger.