BitLife is an implementation of life using boolean operations (AND, OR, XOR), computing each new cell from 9 bits (itself & neighbours). It's performed in parallel on the whole image by bitblit operations (with hardware accelearation where possible). This also allows many parallel life games to run in each bitplane of the screen, giving a translucent blending effect. A proof-of-concept Python (pygame/Numeric) implementation and an xscreensaver hack are included.
ColdSpot is a simple screen locker for X. When the mouse is left inside the transparent ColdSpot window, a user-specified program is kicked off to lock the screen. It is probably simplest to use with focus follows mouse or sloppy focus, although it should still work with click-to-focus.
DeskToy is a 3D screensaver for OS X. A complex set of linked pendulums is displayed in perpetual motion. The behavior of the view and the behavior of the model is highly configurable using the screensaver property sheet. The screen saver is shipped in Universal Binary format for OS X 10.4+.
GNUSTEP Live CD contains a lot of software for GNUstep, a free implementation of the OPENSTEP framework (which is also directly used in Mac OS X as Cocoa). It includes excellent applications for RAD (GORM and ProjectCenter). The CD is available for i486, AMD64, Apple Mac PowerPC, and Sun UltraSPARC computers.
LifeSaver is a Mac OS X screensaver that simulates Conway's game of life on screen. The starting configurations for the cells are randomly selected from predetermined configurations and from randomly generated configurations. MandelSaver is a Mac OS X screensaver that draws colorised Mandelbrot images on the screen. The position and coloration of the subset of the fractal displayed is randomly selected.