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.
Zeta Desktop Environment (ZDE) is an X11 window manager and tools with enhanced usability and features for advanced users and developers. Some of its current sub-projects include imp, a library of core functions such as linked lists, zwl, a simple widget toolkit and light X11 wrapper, and zimwm, the window manager.