Orion is a window manager for the X11 windowing system. It is written in Scheme and accesses Xlib via the scx library for scsh. It is in fact a family of window managers that can be nested. This enables great flexibility and efficient handling of X11 applications. It currently comes with four child window managers: a conventional moving window manager, a window manager for stacking windows in a frame, a window manager for splitting windows horizontally, and vertically and a work space manager. It also supports saving the window manager layout and programmatic configuration.
Style is the ongoing C++ port of IBM's SWT for Java, itself deriving from IBM's VisualAge for SmallTalk, with two major twists. First, it is written in 100% ISO-C++ with no specific compiler dependencies, and second, it comes with a threading model design that guarantee that users won't be stuck with busy cursors forever. It currently targets OS X, Win32, and GTK.
Anarchy is a window manager for the X Window System. It is implemented in less than 500 lines of CLOS oriented Scheme code. The implementation language is Gauche Scheme. Despite its small code size, it supports most functions expected of a basic window manager (move, resize, hide, minimize, maximize, list windows, root menu).
Multi-Cursor Window Manager creates a desktop environment that allows simultaneous input from multiple users. Users can work concurrently on different applications or desktop items. Each user gets a uniquely-colored cursor. It works by time-slicing the single system cursor. The state of each user's multi-cursor is maintained and restored just before an XEvent is sent to the system. Up to seven simultaneous users are supported.
libDockApp is a simple library for easily writing Window Maker dock applications, also known as dockapps (those that only show up in the dock). It is very limited and can only be used for dockapps that open a single appicon for each process in only a single display, but this seems to be enough for most, if not all, dockapps.