When I realized the power of AppleScript, I created this script that launches and controls Exposé. It could also be used to control more things like Safari, a word processor, or the Finder.
[robg adds: In order to compile this script, you'll need to tell Script Editor where it can find SpeechRecongitionServer. Thanks to locate, I found it relatively quickly; it's located on this path:
/System -> Library -> Frameworks -> Carbon.framework -> Versions -> A -> Frameworks -> SpeechRecognition.framework -> Versions -> A -> Resources
In Script Editor when it asks for the location of the app, click Browse, then hit Shift-Command-G (Go to Folder), and enter the above path. The quickest way to do that is to type /Sys, then press the Tab key, then type Lib, press Tab, etc. Each time you press Tab, the directory will auto-complete. The "hack Exposé" and "unhack Exposé" options in the script implement this hack to change the way Exposé's F11 (Show Desktop) function works.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060719043351929