Since I've been hacking Clojure with Slime on Emacs, I've found myself wanting the Caps Lock key to work as the Control key. This makes some of the key combinations with Emacs easier to hit. Leopard makes this easy (almost too easy!).

First open "System Preferences", and select the "Keyboard And Mouse" preference pane.

Then click on the "Modifier Keys" button.

Finally pick Control for the Caps Lock key. Note that I made Caps Locks and the Control keys work as Control. Initially I swapped the functionality of the keys and found that years of using Control in the old location made me hit it too often. Since I rarely used Caps Lock, I decided to just make both of them Control.

QED!