Been to web sites where all links are the same colour, even though you have clicked some before? Wish to tell them apart?
It is a Greasemonkey script for Firefox. By default only rillion.net is affected, add your own "misbehaving" sites.
Unvisited links are in blue
Visited links are in purple
Active (hover - if supported) links are in red
Example before and after screen shots versus this page:
Back to my code page.