Xtacy is a graphics hack for X11. Xtacy will display bouncing shapes, rotating palettes, a couple fractals, a kaleidascope, and lots of more stuff in its own window, or in the root window of the display. There are cycling palette modes, static modes, and animated modes.
Release Notes: Version 1.14 adds the beginnings of support for 16-bit and 24-bit bit displays (although 8-bit PseudoColor is the best supported still). It also adds 9 more modes, including "-blob" and "-tag". Palette files of RGB-triples are now supported as well.