Switching between multiple open Adobe Photoshop documents doesn’t require you to make a trip across the screen to click a different document tab, or moving windows around (if you don’t use the Application Frame in Photoshop) – a particular pain if you’re lucky enough to have a 30-inch LCD screen.
Command + ~ (tilda) or my favorite method, Control + Tab, switches between your open documents, and saves precious micro-seconds in your day.