Wow Enso is probably the best creation ever. My alt-tabbing days are finally over!

“Enso is dead simple to use. You just hold down the Caps Lock key and type an Enso command, which is displayed in a translucent overlay. Once the command is typed, you simply release the Caps Lock key to activate it, and the overlay disappears. If you type fast, it all happens in a flash. For instance, to launch the Firefox Web browser, you just hold down the Caps Lock key and type “open firefox.” To look up the meaning of the word “proclivity,” you just hold down the Caps Lock key and type “define proclivity.”

http://www.humanized.com/