JavaBoard for FICS - A Java Applet allowing to play on the Free Internet Chess Server. Not very featureful, but gets the job done if you can't install an interface. Freeware, Platform independent.
Knights Chess Interface - Knights is a relatively new graphical chess interface for KDE. It is, however, already quite featureful and very nice looking. Doubles as a chess engine front end. GPL, Unix (KDE) only.
