If you don't use your capslock/numlock/scrolllock on your keyboard you can use those LEDs to indicate hdd, network or even cpu activity (kernel must support it) by writing the appropriate command to the sys interface like this
echo "disk-activity" | sudo tee /sys/class/leds/<your LED>/trigger
Does your motherboard have a parallel port header? Connecting some LEDs is trivial. Writing a short C program to display CPU utilization on LTP is not that hard either. There goes your weekend.
