CDE. The Common Desktop Environment was developed by HP, IBM, Sun, etc. It was the graphical desktop that you got in UNIX back in the day. It has now been open sourced, and is quite workable, if a little limited (no integrated support for anything newer than 1990 or so, so install your own wifi widgets, and bluetooth apps, etc.). It is the desktop I used for many years, and I'm delighted to have it available again. It's very customizable and fast as all get out. http://sourceforge.net/projects/cdesktopenv/
I always liked CDE. If you didn't know, they actually open sourced it a couple years back, and the last update was on May 9th. I actually tried compiling and running it on my laptop, but found out that you had to draw your own icons for everything since it didn't support .png icons or anything, so I just gave up and used WindowMaker instead (the whole system uses about 30 megs of RAM on startup, and I get dockapps. According to htop, WindowMaker itself only takes up about 2.5 megs of RAM.