Go Pack is a collection of (Java) GUIs and engines to play Go. Currently included are :

GoGui 1.4.9 – http://gogui.sourceforge.net
JaGo 5.0 – http://jagoclient.sourceforge.net
GnuGo 3.8 – https://www.gnu.org/software/gnugo
Fuego 1.1 – http://fuego.sourceforge.net
Pachi 11.0 – http://pachi.or.cz
AmiGoGtp 1.8 – http://amigogtp.sourceforge.net