EDE - Equinox Desktop Environment
Main goals of this project are simplicity, speed, minimal memory usage (if possible), good look and fell and stability. That does not mean it will be for 8086. It's FLTK-based.
foXdesktop
Lightweight desktop environment, uses Fox multiplatform C++ widget set. [Open Source, LGPL]
The Definitive Desktop Environment Comparison
Compares UI and usability of several desktop environments (DEs) that are widely used, admired, reviled: Windows XP Luna, BeOS 6 (Dano/Zeta), Mac OS X Aqua, Unix KDE and GNOME. Larg…
The GUI Gallery
Surprisingly large and thorough Graphical User Interface list, with timeline, screenshots, downloads, links. Very useful resource for students of computer interfaces.
Xfce Desktop Environment
Runs on FreeBSD, Linux, SunOS/Solaris; English, French, German. Description, downloads, CVS, screenshots, bug reports, fora. [Open Source, GPL; SourceForge.net]