Divvy makes window management a snap on your Mac
The window management tools in Windows and OS X were created at a time when average screen sizes were a fraction of what they are now, and yet it seems there has been very few changes to how they work. Probably the biggest evolution is Windows 7's ability to snap windows to the sides or top and bottom of your screen and resize them accordingly.
While Macs don't have a feature like that built-in, there's a relatively new utility called Divvy that can do some very nice window management at the touch of a hot key. I should be clear that Divvy does not replicate the Windows feature discussed above; instead it does something better.
Divvy allows you to divide up your screen into variously sized rectangular work areas using a grid, then assign a hot key to each one. Then you can snap any active window to a work area using a corresponding hot key that you set. Instead of just resizing two windows equally on the left and right of your screen, you choose how much room to give each one -- though you could use it to divide your screen evenly if you wanted to. You can also resize windows to a grid in a freeform click-and-drag fashion.
Divvy costs $14 US, however they have a demo available that is not time-limited (though it will remind you often to buy a license).