Jason Rehmus offers some great productivity advice on the Frictionless blog:
Moving your hand the short distance from your keyboard to your mouse may not take much time, but it can interrupt your workflow enough to distract you and cause enough friction to slow you down. That’s why you should learn the keyboard shortcuts for every program you rely on.
One of the best things I've ever done to understand how my computer makes a better tool has been learning the shortcuts. On the Mac, that of course is mainly done with the keyboard, but Lion also brought trackpad gestures. Those have been handy as well, when necessary. And on iOS, it's a good idea to learn the gestures on the iPad if you have one, or for any app that offers gestures as a quick way to accomplish a task. Gestures are the keyboard shortcuts of iOS.
Rehmus focuses on the desktop, and has some great hints at getting you started.