Windows/Mac: Divvy takes Windows 7's window-lock Aero Snap powers to the next level — originally on Macs, and now on Windows, too. Using a small Divvy windows, or keyboard shortcuts, you can line up your app windows any which way you want.
Divvy's use is explained in the screencast up top, but to summarise, Divvy provides a small, gridded window in which you can arrange your open windows into neat order: side by side, half-and-half vertically or horizontally, split up five windows to fill one monitor, or combinations of all those and other configurations. You'll use the Divvy mini-window to set up your ideal window configurations, but you can then set keyboard shortcuts to enact those configurations later, no excessive clicking needed.
Divvy is a free download, with some nags, for Windows and Mac systems; buying a $US14 licence removes the nags.