FVWM-Crystal aims to create an easy to use, pretty, but also powerful desktop environment for Linux or other Unix-like operating systems. It uses the following programs: FVWM as a window manager and "main core"; different ways to provide icons on the desktop including support for many file managers and custom commands; xterm, aterm, mrxvt, or urxvt as terminal emulators; MPD or XMMS2 as music players (there's built-in support for controlling these programs), and several other tools for different functions, like setting a wallpaper or taking screenshots.
X Persistent Remote Applications (xpra) is "screen for X". It lets you run applications remotely (like ordinary X or VNC), but unlike ordinary X, these applications are "persistent" if you lose your connection, or even if you want to switch to another computer. Also unlike VNC, they are ordinary applications on your desktop managed by your window manager, not trapped in a box.
Wimpiggy is a library for writing EWMH-compliant, compositing window managers using Python and GTK+. The goal is to make writing a window manager as easy as writing a PyGTK application. This library can be used to build a trivial, working window manager in only about 40 lines of code.
JoyWM (formerly known as Linux Multimedia System or LMMS) is a multimedia GUI written in Python/Pygame. It provides an easy-to-use GUI for tasks such as listening to music, watching movies, viewing pictures, and playing some games. It is appropriate for use on a TV and can be controlled with a joystick (or a keyboard if no joystick is present).
WnDO (formerly Fbdo) is a small suite of complementary tools for adding behavioral extensions to Gnome, Xfce, Fluxbox, and other window managers. WnDO offers a plugin platform for tweaking the desktop environment. It focuses on modifying behavior, rather than adding desktop widgets. It has minimal dependencies, other than Python. Included modules handle window alignment, simple window tiling, process management, wallpaper management, and custom keyboard shortcuts. Wallpaper management capabilities include per-workspace and randomly-selected wallpaper. It performs its own key grabbing in order to avoid interaction and conflict with the equivalent window manager facility. It requires CmDO.