Hammerspoon - This is a tool for powerful automation of OS X.
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).
ReIcon - ReIcon is portable freeware that enables you to save and restore your desktop layout.
SizeUp - SizeUp allows you to quickly resize and position your windows with keyboard shortcuts or a handy menu bar icon. Arranging windows on Mac OS X is tedious and imprecise.
VC Starter Kit - Everything you need to look like a Venture Capitalist