Mac: OS X doesn't have much in the way of window management built into it, so if you're looking to control window placement and size with your keyboard or trackpad, you'll have to look elsewhere. Flexiglass is an app that does just that.
Flexiglass has been around for a while (and we've mentioned it in passing before), but it's still a solid app when you need it. Essentially, Flexiglass allows you to control your windows location and size with either keyboard shortcuts or gestures on a trackpad.
With just a tap of a keystroke you can push a window to a corner of the screen, resize it, or organise all your open windows in a set layout. It's a handy app, but if you're not sure it's useful for you, you can grab a 15-day free trial from the developer's site.