Mac OS X Tip: Switch Applications from Keyboard
A great Mac OS X keyboard shortcut allows you to switch back to the last application which was frontmost by holding down the "Apple" modifier key and pressing the Tabl key. I love this feature for bouncing back and forth between two different applications.
There are variations to this key combo: press and hold the Apple key, hit the Tab key once but continue to hold down the Apple key. This brings up icons for all the running applications in the middle of your monitor, and now you can keep hitting the Tab key until you get to the application you want, OR, use the mouse pointer to select one.

