JagoClient is an
The program has been written in Java, which means it is available on all modern platforms. JagoClient has been translated into a lot of languages. Your local language will be used automatically.
JagoClient is freeware and open source.
The Windows version of JagoClient includes a Windows binary of GnuGo, the Go playing program. See their webpage for more information, the source and the license.
In case of bugs or comments, contact me via my home page.