Ion is a tiling tabbed window manager designed with keyboard users in mind.
Ion was written as an experiment on a different kind of window management model. It tries to address the navigation problem by dividing the screen into mutually non-overlapping frames that take up the whole screen. Big displays have so much space that this should be convenient and smaller displays couldn't show more than one window at a time anyway. The frame layout is, of course, dynamic and different on each workspace. Given the organised tree based instead of an unorganised coordinate-based frame layout, moving between the frames can be conveniently done from the keyboard. As in PWM, the frames may have multiple clients attached, each indicated with a tab.
Toga II is a chess program, derivative of Fruit created by Thomas Gaksch. It has more chess knowledge and perhaps a better search algorithm. It is based on Fruit 2.1 and is free.