aewm is a minimalist window manager for X11. It has no nifty features, but is light on resources and extremely simple in appearance. It should eventually make a good reference implementation of the ICCCM. A few separate programs are included to handle running programs, switching between windows, etc.
AfterStep is a Window Manager for X which started by emulating the NeXTSTEP look and feel, but which has been significantly altered according to the requests of various users. Many adepts will tell you that NeXTSTEP is not only the most visually pleasant interface, but also one of the most functional and intuitive out there. AfterStep aims to incorporate the advantages of the NeXTSTEP interface, and add additional useful features.
Athene is a desktop system for Linux that uses its own graphics drivers for high speed access to your graphics card. Because the Athene desktop and its applications have direct access to the graphics hardware, they have a significant speed advantage over conventional X applications. Athene is also backwards compatible with your existing X11 software. It features a highly responsive interface, scalable icons, translucency, alpha blending, Unicode support, and Windows compatibility.
bbkeys is the keygrabber for the Blackbox window manager. bbkeys handles all keybindings and keyboard shortcuts for Blackbox. It uses Blackbox's Image classes for rendering its look and feel, so bbkeys will draw itself to match whatever Blackbox style is used. It is highly configurable via the bbconf GUI utility, the included bbkeysconf.pl perl script, or via hand-editing bbkeys's config file.
Blackbox is yet another addition to the list of window managers for X. It is written in C++, sharing no common code with any other window manager (even though the graphics implementation is similar to that of WindowMaker). It features small code size, a fast interface with simple menus, multiple workspaces, decorated windows, built-in graphics code to render solids, gradients, and bevels on the fly, and more.
CTWM is a highly-configurable window manager based on the classic TWM window manager. It supports xpms, multiple workspaces, advanced icon managment, animated icons and backgrounds, 3D titles and borders, etc. It offers rudimentary Gnome support and is backwards-compatible with TWM.