CGoban 2
CGoban 2 was an SGF editor and client for the Kiseido Go Server written and maintained by William Shubert, which is now obsoleted by CGoban 3.
The software is available in several languages. It handles variations quite well. Annoyingly, it puts a "circle" mark on the current move, which can look odd when viewing the file in another program.
CGoban 2 is distinct from an earlier program by the same author called CGoban. Unlike CGoban, both CGoban 2 and CGoban 3 are not free software. William Shubert claims that by making both the protocol and the source code closed, he can innovate the features of KGS without having to support other clients.