yahoo! vs. google is a very cool visualization tool to compare results. I think the addition of numbers or a bit of instruction would have been helpful, but once you get the concept, it's sweet.

the two rows of dots represent websites in load order, left=#1. So you can easily spot divergence.

when you mouse over the dots, "touch the dots" is replaced with the URL for that position

here you can see a search for "information architecture" in which a webmonkey index page on design topics is #1 at google, while Yahoo's #1 is jesse's IA resources page. However, I wonder how accurate this is, since when I do the search a second time on google straight, the #1 is argus, then the webmonkey tutorial on IA, while yahoo shows jjg then argus. Maybe slow on the updates?
Still cool visualization idea.

For a breif time, you can compare the new Yahoo! Autos to the old .