Here is a list of various desktop environments I’ve heard about.
* LXDE: The Lightweight X11 Desktop Environment is especially designed for computers with low hardware specifications like netbooks and mobile devices.
* EDE: The Equinox Desktop Environment is small Desktop Environment built to be simple and fast. It is based on a modified FLTK library.
* Athene Desktop: A Commercial desktop with its own graphics server , although it can also display X11 applications for compatibility.
* Metisse: An experimental X desktop which uses a virtual X server, a special version of Fvwm, and Open GL support to implement various window effects, including rotation, scaling and blending.
* JD4X: The Java Desktop for X aims to provide a Java based desktop that can run both Java and native applications. It is initially only available for Linux x86 platforms.
* 3D-Desktop: an OpenGL program for switching virtual desktops in a seamless 3-dimensional manner on Linux.
* XD640: A simple graphical desktop environment for X designed for small screens and slow processors.
* XPde: A Windows XP-like desktop environment designed for Windows users migrating to Linux.
* ROX: An attempt to bring some of the good features from RISC OS to Unix and Linux. It Includes a desktop environment based around a file manager.
* 5dwm: The Indigo Magic Desktop for Linux.
* UDE: Unix Desktop Environment- early stages of a new window manager written using only XLib, rather than special GUI libraries.
* CDE: The Common Desktop environment is a commercial graphical user interface for UNIX in its various flavors (AIX, Digital UNIX, HP/UX, Solaris, UnixWare, etc.).The CDE incorporates the down window manager.
* KDE: It is modern network transport desktop environment. It contains a base set of applications such as a window manager ( called Kwm), web browser, instant manager and integrated help system, all with a consistent look and feel, and translations over 50 languages.
* GNOME: (pronounced “ Gah-NOME) project’s aim is to build a complete, user friendly desktop based entirely on free software. It is not a window manager, and in fact has to be run in conjunction with a window manager.
* Xfce: Xfce is a lightweight desktop environment for UNIX platforms. It is similar to the commercial CDE, and is now based on the GTK + toolkit.
If you know of any others, or think I should feature any of them in more detail, please let me know.