Here's a couple more to be aware of:
Delta Search (claims to use the combined power of Google, Bing and a couple of other search engines). It hijacks your browser and is a really persistent nasty little bugger - just refuses to go away. Furthermore, somehow it randomly eats cpu cycles so your system becomes unbearably slow (like you get allocated about one cpu cycle a minute). It downloaded with a battery power monitor I needed for a netbook (I must have failed to untick a browser search toolbar). I really thought the netbook had died and was about to bin it - then googled Delta search from another machine.
To get rid of it you have to use Remove Program (more than one program gets loaded into the registered program list) and then scan your registry to get rid of registry entries (I used CCcleaner to do that).
Another one from the same source but on a different netbook was
search.conduit.com - this seemed much easier to get rid of (maybe because of my frustrating experience with
Delta Search.
Let's be careful out there!