Server Clients

CGoban 3
Includes an editor for SGF go files and a client for the Kiseido Go Server.
http://www.gokgs.com/download.xhtml

Complete Goban
Go program for Unix and X11. Local, internet or modem play, as well as .SGF-compatible record and replay.
http://www.igoweb.org/~wms/comp/cgoban/index.html

The gGo client
gGo is a Go board, SGF editor, client for the Internet Go Server and an interface for playing with GNU Go. gGo is written in Java and available for Linux, OS X, OS/2 and Windows.
http://panda-igs.joyjoy.net/java/gGo/

GoKnot
GoKnot is an IGS telnet client and a Go player (playing locally against the GnuGo engine).
http://www.dybot.com/GoKnot/index.htm

Jago
Java-Client, Internet Go Server client, a Smart Go Format go game viewer and a point to point go player.
http://www.rene-grothmann.de/jago/

Java Go Client
A java plug-in to run Go against a server.
http://panda-igs.joyjoy.net/java/jgc15/index-e.html

TanGo
A freeware IGS and NNGS compatible Go client.
http://www.amourtan.com/

Xgospel
X-Window client for internet go servers.
http://gailly.net/xgospel/index.html