Hit a key to "move and resize active window"
I use a little app called Divvy to do this. You can set up a global hotkey to bring up Divvy. And then within Divvy you can set up hotkeys that will snap the current window to a specific location and a specific size. It's great for quickly doing 2-up Finder windows for copying things back and forth. Or a Finder window on the left and a CyberDuck window on the right for remote copies. One of those apps that, when it's not on a Mac, will make it feel a little bit broken.