I've actually been looking for something like this, and Moom seems to do the trick. It's got some nice customization, so I can at least set my own shortcuts for different areas of the screen. It works really well since I don't like straight 50/50 screen splits (I prefer a sort of pseudo-golden ratio layout -- Moom can't do it precisely, but it's close enough).

Pretty good use of $10, I think, unless I suddenly need that $10 for an emergency, like beer or coffee or a raw turkey. So, thanks, even if I'm stuck without a supply of raw turkey for a week.