I was talking with a couple of security folks about my CSS/JS History Hack, two had come up with some very simple and elegant solutions.
Richard Bejtlich (TaoSecurity):
"I don't keep a browsing history (days = 0) on Firefox so I have nothing to show"
"Obviously, the CSS trick just tries to load a page with a link to the target websites and then looks at the color of the hyperlink to determine if the it has been visited. This is based off of the browser preferences settigs for links/visited links. If I change the color of my visited links to the same color as non-visted ones, then the cute trick didn't work. The problem is that this would still extremely effective as how many actual users would go into their browserr settings a tweak this? That's right, not many."
Two tricks that some power users can try out.