The corporate goal of consolidating sources of information collection is one more step successful now: Yahoo is no longer a real search engine.
Yahoo's Slurp is no longer spidering the internet, or at least my site with only 30 hits last month when it would typically hit my site a couple thousand times. Yahoo's results are now taken from Microsoft although it seems that they rearrange results just like other search sites that don't run their own spiders such as Hotbot and Lycos.
The notable search engines and their respective spiders that are not run by Google or Microsoft are below...
Entireweb - Uses the Speedy Spider, based out of Sweeden.
Yandex - Russian search engine with operations here in America.
Baidu - Chinese search engine, doesn't seem to adapt to American visitors though.
Blekko - Uses ScoutJet.
Alexa - Yes, they do actually run a search spider, ia_archiver.
There are other search engines that really don't break double digit hits on a monthly basis. I think Entireweb, Yandex and Blekko are the most deserving of most people's consideration.