I love the Window Switcher feature (invoked by Win+Tab) in Windows 7 and Vista.

If you'd like to invoke this feature with a mouse gesture, do the following:

1. Download gMote. As you can see, the application allows you to launch any application with a mouse gesture.

2. Create a gesture which will trigger the following command:

C:\Windows\system32\rundll32.exe DwmApi #105

(the #105 is a part of the command - it points the system to a required event; the command actually triggers a second state of Window Switcher (Ctrl+Win+Tab), where you can scroll through the windows with a scrolling wheel).

3. Configure gMote to react to gestures while the middle mouse button is pressed.

Enjoy!