We always say it, the next search engine is just a click away, but we hardly ever believe it. Your next click away to Exalead may very well turn you into a believer.
Established in 2000 in France by Francois Bourdoncle, Exalead features everything a mature search engine needs and then some. Google might run away with the news headlines but Exalead had many of its newer features before Google did.
Exalead has some very strong searches such as search within results (handy!), proximity search using the NEAR operator (something Matt Cutts keeps explaining we want but really don't need...), regular expressions, wildcard and phonetic search. To name just a few.
Their image search has face recognition powered by LTU Technologies. See the difference searching for paris or Paris. Like Google, Exalead's face recognition system recognizes that something is a face: it doesn't know whose face it is.
They have a wonderful Wikipedia search which features either a preview thumbnail or a main image used on the Wikipedia entry.
Also on the page, a very handy tag cloud.
Is Exalead replacing Google? No. Not yet. Not by a far stretch. Exalead's market share is a little over half a percent. But from April to May that market share grew 40 times faster than Google did.