Google has proved that a good search engine has nothing to do with looks(1). They came out of nowhere with the simplest UI ever, no adds, no categories, nothing (at least at first sight) and rule the Internet. Suddenly being at the top of the Google result page was what everyone wanted and page rank became an obsession for some people.
But now, there's a new search engine called tafiti (Swahili for "do research") that has a very appealing UI (done with Silverlight). Obviously Microsoft or any other company couldn't compete with Google's simple yet efective design so they went a little further and tried a new thing.
At first look Tafiti is a cool web search site. It also has a simple way to show the results, so far with no adds, but it also has a more complex way (see it yourself).
Another cool feature is the possibility of saving and tagging results right away. Yes, I know Google does that, but Google saves every little search you did (some of them you probably wish it didn't). Tafiti lets you drag your result to the right to save them and tag them. It also shows you results from feeds, news, images and books.
One more thing, if you tafiti my name I'm at the top of the results so it looks the index engine is working just fine ;)
(1): Goomez has proved that too, but that's for another post :)