A free and simple to use window manager.
Ranked in these QuestionsQuestion Ranking
Pro Free and open source
All windows can be controlled with keyboard shortcuts, so no mouse is needed. This makes for a fast way to control windows.
Pro Simple hotkeys
Spectacle offers easy-to-remember preset hotkeys.
Pro Great UX
Spectacle is easy to use and configure. It's plug and play.
Pro Low footprint
Spectacle only uses up 18-19mb of RAM, which meant there is not much overhead to using this app.
Pro Multi-monitor support
Con Impossible to add new functions
While keyboard shortcuts can be changed for the available actions, there is no way to add custom actions which limits the functionality of the app.
Con Doesn't work with any Adobe products
There are some apps like Adobe Reader that do not work with Spectacle. Basically any app with a heavily customized UI that breaks OS X accessibility will not work correctly under Spectacle.
Con Limited window sizing capabilities
You can use 1/2 of the screen vertically and horizontally. (divide into 4 part) And you can use thirds too, but only the left and right third, you can not use the 1/3 in the center. There is no way to do more granular distribution.