BlindSearch is an interesting novelty: you type in a search request, it gives you back the top 10 results from Yahoo!, Google, and Bing! (without telling you which is which). Then you pick which results you think are the best.
The results after 8 weeks: Google: 41%, Bing: 31%, Yahoo: 28%. Not a huge difference, if you ask me.
(from the Search Engine Watch blog)