I want to make a quick mention regarding one of the most useful utilities I've found in recent days: SizeUp. It allows you to resize and reposition windows using keyboard shortcuts. It's no secret that I like my screen real estate, and making the most of it is a big deal to me. You can sit and resize windows all day, but I'd rather hit a couple of keys and have everything in place.
SizeUp offers half-screen (vertical or horizontal) and quarter-screen sizing (easily positionable in any corner), as well as a true Windows-style maximize function. You can also set a custom size for the "Center Window" option, which resizes the window to the specified dimensions and positions it in the center of its current screen. Not the screen you want? The last set of shortcuts lets you jump the window between existing monitors in your setup.
The hotkeys are configurable, but the defaults (surprisingly) didn't conflict with any of my extensive collection of shortcut combinations. SizeUp is shareware, but you can pay what you think it's worth (Fair licensing). A suggested price of $9.99US doesn't seem at all unreasonable to me. If it's useful to you, but not that useful, a minimum donation of $2.99US is requested. The maximize function alone is worth that. Developers Irradiated Software also offer a "lite" version called TwoUp which can do the split screen trick on its own, free. Grab a fully-functioning demo of SizeUp at the Irradiated Software website.