ShiftIt

ShiftIt is a small, nimble utility that allows you to quickly organize and full-screen your Mac OSX windows. It's similar to the "Aero Snap" function in Windows 7.

Simply press ⌃⌥⌘ and the arrow keys to quickly send a window to take up the whole half of your monitor.

Or press ⌃⌥⌘+F to maximize it and take up the full screen faster than you can even think about pressing that unreliable green circle.

It has only two options: Start at Login, and Hide Icon. You can also customize the keyboard shortcuts. That's it! Simple and useful.

Download

Note: This fork is discontinued since the original project has picked up steam again. Please head there for the latest updates.

Download ShiftIt from the Official Repository

Latest version: 1.5.2, released September 21st, 2012

Unfortunately builds for older versions of OSX are not currently available. ShiftIt is Open Source and easy to build though, so you may be able to build your own! See more at the GitHub Project Page