Wolfram Alpha Screencast
Wolfram Alpha is a brand new search engine that works in a totally different way to the others. Instead of returning a bunch of websites as results, Wolfram Alpha will actually answer your question (or attempt to). It does not refer you to other websites. It has not launched as of yet, but the link is to a screen cast where Stephen Wolfram will walk you through Wolfram Alpha.
It looks incredibly interesting and very clever. It is the kind of thing that just might tip the scales away from Google (although it is a totally different concept to Google).