I happed to wonder if there were any enhancements to the keyboard I was using and found the following interesting links. The pages describe how to modify the key mappings of the Microsoft Ergonomic 4000 Keyboard, primarily to change the Zoom buttons in the middle of the keyboard to a scroll button (which is more useful to most people with good eyes).

Information on the Keyboard Hack and a good way of implementing it:
http://huddledmasses.org/hacking-the-natural-4000-keyboard/

Downloadable configuration file (easy):
http://joshhighland.com/blog/2006/09/14/hacking-the-microsoft-natural-keyboard-4000/