shiftit – Project Hosting on Google Code

This application will let you resize and move your windows without having to using a mouse. Following are some of things you can do with the Shift It:

Shift the focused window to left/right/top/bottom half of the screen.
Resize the focused window to fill the whole screen.
Move the focused window to the center of the screen.
Shift It is a great tool that lets you organize your windows. Now you can read documents side-by-side without having the pain of manually resizing the windows.
(Link: shiftit – Project Hosting on Google Code)