x9wm is a clone or fork of the 9wm and w9wm X window managers. It is a light alternative for the Mac OS X desktop. All of its source code is contained in a single file. It supports an alterate red colored cursor. It is very light on resources, quite fast, very simple, and easy for long programming, editing, or Web work sessions. You can blend it with Nitrogen and Wbar to create a simple but elegant interface without iconic or stylistic clutter. It does not decorate windows with borders, and it is modal, controlled with the mouse.
MIcroscopic Window Manager (MIWM) is a fast, small, minimalist, and extremely reliable window manager. It is designed to do the job very simply and unobtrusively, without constraining power users. It features optional auto-tiling, desktop cleanup, a user-defined root menu, optional previewing of hidden windows, variable numbers of virtual desktops, and configurable window behavior. It includes a simple, very effective memory management utility for leak detection.
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.