teoma.com
Best engine out there right now.
If you can get your sites up to the top on Google, then its a great source of free traffic, but since November, Google results have really turned up shit. I have noticed I am not able to find half the stuff I search for now, and just end up using Teoma because they'll give me what I'm looking for, or help me find it.
And who knows about Yahoo, I hope they don't go pure Inktomi again, damn PFI engines always suck ass.