Assuming you’re an obssessive compulsive Mac user who goes Monk-like bonkers when your Mac’s open windows get scattered all over the screen, you’ll like SizeUp:
SizeUp allows you to quickly position a window to fill exactly half the screen (splitscreen), a quarter of the screen (quadrant), full screen, or centered via the menu bar or configurable system-wide shortcuts (hotkeys).
SizeUp is really slick and creates neatly arranged windows on your Mac’s screen. One could ask the question, “Why bother?” Elegant use of the Dock prevents the need for tidy, unionized window management. It’s a solution looking for a problem. Unless you’re a Monk-like Mac user.
Companion window manager Cinch is equally useless at half the price.