A Graphical OS for the Atari 8-bit
Atari 8-bit fans have long hankered after a GUI similar to GEOS on the Commodore 64. Diamond GOS went some way to addressing this deficiency, and since then there have been several creditable attempts at implementing a GUI OS on the A8. Now there's another one in the pipeline: an as yet unnamed project which aims to bring a pre-emptive multi-tasking graphical operating system to the 8-bit Atari.
This is a seriously impressive project with ambitious goals, and it looks great considering the hardware it's running on.