[Original Link] I have a nice row of almost unused function keys on my Apple keyboard. I wanted to map them to do some of my regular tasks, so that F1, for example, would open Palm Desktop and prompt me to search for an address.
Keyboard Maestro allowed me to do this easily and has lots of other cute features which you can use if wanted and disable if not.
This is also a very nicely tailored use of shareware. The free version does enough for many people without nagging, but you can pay $20 if you want that little bit more. Recommended.