Twindy is a window manager for linux (& possibly any system running an X server?) inspired by Tracktion, the multitrack audio editor/sequencer for Windows and OS X. Twindy tries to apply Tracktion's workflow, where everything is on screen at once, to a window manager. As such, there are two panels, a main panel where new windows/programs open by default and may be selected using tabs, and a lower panel, which can only hold one window/program at a time.
Viper Window Manager
Viper Window Manager (VWM) is an extensible window manager for the console. Built on top of libpseudo and libviper, VWM is more visual alternative to Screen.
VTWM is an extension of TWM, implements a Virtual Desktop that sports a fully-configurable 3D interface. VTWM's is user-configurable: The VD's initial scale, size, and position. The colors of the VD, the real screen, and the windows within. The windows that may or may not be represented within. External image (XPM) files can decorate the VD and the real screen.
w9wm is a quick & dirty hack based on 9wm that provides support for virtual screens.
Waimea is a virtual desktop window manager for X11 designed to be fast and highly customizable. It uses Blackbox image rendering engine (Blackbox styles support) and can use Xrender extension for rendering fonts (anti-aliased font support).
WeeWM is a window manager for XFree that is fast, ultra light, all can be done with keyboard.
Whimsy is a highly hackable and dynamic window manager.
Wind is a window manager for the X Window System. It supports virtual desktops, optional Xft font rendering, and is fairly standards-compliant. It provides classic overlapping window management with click-to-type focus. Windows are never minimized.
Window Manager From Scratch
WMFS (Window Manager From Scratch) is a lightweight tiling window manager for X. It can be configured with a configuration file (made with libConfuse), and it supports Xft (FreeType) fonts.
WindowLab is a small and simple window manager of novel design. It has a click-to-focus but not raise-on-focus policy, a window resizing mechanism that allows one or many edges of a window to be changed in one action, and an innovative menubar that shares the same part of the screen as the taskbar. Window titlebars are prevented from going off the edge of the screen by constraining the mouse pointer, and when appropriate the pointer is also constrained to the taskbar/menubar in order to make target menu items easier to hit.
Using wm2, you can move windows around the screen, resize windows both horizontally and vertically, hide windows, restore hidden windows and delete windows. wm2 also adds a stylish frame to each managed window.
wmG is a window manager for X that is minimalistic, and designed for use with Gnome. It is GTK based, and so matches GTK programs better than any other window manager. It is fully ICCCM and Gnome compliant, as well as partial Mwm compliance.
wmii is a dynamic window manager for X11, which is highly customizable and usable with keyboard and mouse. It supports conventional, tabbed and tiled window management with low memory footprint. It is highly modularized and uses an inter-process communication interface which conforms to the 9P2000 protocol of Plan 9.
a window manager for X. It's based on wm2, and it retains a similar look and feel
wumwum is a window manager manager. it can turn emwh compliant window managers into a tiling window manager while retaining all initial functionalities.
xmonad is a tiling window manager for X. Windows are arranged automatically to tile the screen without gaps or overlap, maximising screen use. Window manager features are accessible from the keyboard; a mouse is optional. xmonad is extensible in Haskell, allowing for powerful customisation. Custom layout algorithms, key bindings, and other extensions may be written by the user in config files. Layouts are applied dynamically, and different layouts may be used on each workspace. Xinerama is fully supported, allowing windows to be tiled on several physical screens.
XSWM is a fast and light window manager for Linux/BSD based on EvilWM. Features: No mouse needed, key shortcuts, and on screen display of messages.
yeahwm a minimalist wm for X based on evilwm. Features include: Sloppy Focus, BeOS-like tabbed titles, Support for Xinerama, and good keyboard control.