Magnet Window Manager - Magnet Developers
VC Starter Kit - Everything you need to look like a Venture Capitalist
Spectacle App - Move and resize windows with ease.
SmartWindows.app - Auto arrange all your app windows, whether on one screen or many with a single click!
Moom - Move your mouse over the green zoom button in any window, and Moom's mouse control overlay will appear (as seen in the above animation).
PingPoint - Never miss a Mark Zuckerberg signup to your app ever again