You won't believe the time you save by just binding 'esc' to a mouse button. 'enter' also, but to a lesser extent. Every time you're mousing and a dialog appears, you have escape and cancel. It's also very useful in photoshop and games.

I learned it from working on AutoCAD with a puck on a tablet. One of the buttons was binded to 'esc', and the right button acts as an enter. Later when I switched to mouse, the 'esc' mouse button was the thing I missed the most.

I've also made some statistics: http://inodetelic.com/autocad-command-statistics/

Puck UIs (https://www.dropbox.com/s/7v099r086r0cyu1/some_tablet.jpeg?d...) were good at the time for drawing programs because screen space was precious.