Sawfish!

Dexpot turns your monitor into up to 20. It creates and manages virtual desktops and enables you to work far more efficiently and comfortably with many simultaneously opened windows on Windows 95/98/ME and NT4/2000/XP/2003/Vista (incl. x64).

WinSplit Revolution is a small utility which allows you to easily organize your open windows by tiling, resizing and positioning them to make the best use of your desktop real estate.

Openbox is a highly configurable, next generation window manager with extensive standards support.

Preme is a free software for Windows which lets you add cool desktop features and enhances the desktop functionality.

Adds eye-candy effects to windows (and start menu) like deformations (e.g: jelly windows - that makes moved window wiggle like being made from jelly; or fold - which hides windows by folding up horizontally, and unfolds when showing), physics (e.g.: keep momentum - making window to conserve move momentum; or bounce - that makes windows bounce upon receving focus ) and other SFX (e.g.: pixie dust - which makes moved window to leave a trail of twinkling pixie dust; or close puff - which displays puff cloud below cursor when closing window). »

TotalSpaces provides a grid of spaces on OSX Lion

Mission Control, formerly Exposé, is a feature of the OS X operating system.

KWin is a window manager for the X Window System, and is in the process of becoming a Wayland compositor. It is an integral part, and the default window manager of the Plasma Workspaces, but it can also be used on its own or with other desktop environments.

Bluetile is a tiling window manager for Linux, designed to integrate with the GNOME desktop environment. It provides both a traditional, stacking layout mode as well as tiling layouts where windows are arranged to use the entire screen without overlapping. Bluetile tries to make the tiling paradigm easily accessible to users coming from traditional window managers by drawing on known conventions and providing both mouse and keyboard access for all features.

Chameleon Window Manager will allow you to control the windows of your programs using customizable buttons added to the title bars of the windows (Always on Top, Minimize to Tray, Minimize to Caption, Specify Transparency, Position window at left/right of screen).The interface supports skins and is very easy to use.

Virtuoz was designed to be a minimal and robust program that allows to have more than one desktop on Windows. It was inspired by Sysinternals Desktops, but uses a different approach, which doesn’t impose the limitations which Desktops is bound to.

Inspired by Jef Raskin, our zoomable user interface shows you all the stuff on your computer on a single surface. Using zoom and pan to view, arrange and open documents feels so right. In minutes you’ll appreciate the simplicity and intelligence of our answer to the traditional desktop. Take a spin and see for yourself.30-day trial available, $24.99 to buy.

WinNumpad Positioner is a lightweight and snappy Windows management tool that repositions Windows using simple Windows Key + Numpad combinations.

mDesktop is a lightweight application that allows the user to utilize multiple virtual desktops. Also, mDesktop integrates with Hotcorners. mDesktop currently supports up to ten virtual desktops.