Keyboard leds are pretty boring. Usualy you know if the num lock is on or if you are writing in upper case
letters. Could we make them do something more useful? Of course.
The keyboard leds can be controlled by a device driver called the misc driver. That driver can control all
kinds of misc things. You could write your own driver to make them blink or light up at any system event.
A program called tleds is available from http://www.hut.fi/~jlohikos/tleds.html. That program will have them
blink based on network usage. One will blink when packets go in, and the other when packets go out.