Code:

http://cache.gawker.com/assets/images/lifehacker/2009/02/Windows_7_Shortcuts_0.4_02.zip

Included:
Win+Left/Right arrows: Dock the window to each side of the monitor
Win+Up arrow: Maximize the active window
Win+Down arrow: Minimize the window/Restore the window if it's maximized
Win+Space: All windows are made transparent so you can see the desktop
Win+Home: Minimize all windows but the current window

* Win+Left/Right/Up now cycle through different window arrangements. Win+Up will cycle between a maximized, and two half height windows. Win+Left/Right cycle between a half width window (on their respective sides, as before) and 2 quarter height windows (again on their respective sides). This gives quick access to 21 different window layouts and makes better use of larger monitors.
* Fixed a bug where Windows would remain transparent after releasing Win+Space
* Fixed a bug where Windows would remain transparent if a key was pressed before releasing Win+Space
* Preferences were completely broken but are now fixed
* Misc UI enhancements

Code:

http://lifehacker.com/5133039/windows-7-shortcuts-enables-the-best-win7-shortcuts-in-xp-or-vista