I generally default to just using one search engine (yes, that one). Blind Search is a service for trying the three main search engines currently in use (Google, Yahoo and the new one with the silly name). Given some search terms, Blind Search shows you the top 10 results from each of the three engines, anonymously, and asks which set got closest to your expectations. Interestingly, I found that honours were spread fairly evenly, and, even more interestingly (given my normal search behaviour) Yahoo edged ahead.
It's also a nice bit of UX engineering: I found myself very curious to know which engine was which, but you can only get to find out by selecting the engine that best matches your expectations, thus feeding useful stats back to the service. Neat.
Tip 'o the hat to Tim at UMBC for the pointer.