Windows 7 introduced a feature to keep your windows organized, called Snap. It allows you to quickly arrange two windows side-by-side, filling up the entire screen. This feature wasn’t critical to me until I starting using a 27″ monitor. With a monitor this size, you’ll want to use a dual window arrangement to take advantage of the screen real estate.
Mac OS X doesn’t come with a similar feature out of the box. However, there are alternative solutions available from third parties. One such solution is Window Tidy. This application provides similar functionality to Snap, but with a slightly different interface. When you start to move a window, a number of layout icons appear over your desktop. You simply drag the window into the desired layout and it will instantly snap into position. I find this interface less error prone than Snap, and more flexible. You can create your own custom layouts if you’d like. For example, I created a layout to center a window on my second (smaller) monitor.
Window Tidy is one of those small, inexpensive apps that you grow to rely on. It can be purchased on the Mac App Store.