AquaSnap - Too many windows on your screen? Stop wasting your productivity.
Hammerspoon - This is a tool for powerful automation of OS X.
WindowGrid - Quickly and easily layout windows on a dynamic grid using just the mouse.
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).
Shiftit - fikovnik has 62 repositories available. Follow their code on GitHub.
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.