Meta Search Or Meta Ads?
"What people may not realize is that many meta search services are now also bringing back paid placement listings and mixing these in among the more traditional editorial-style results that they retrieve. In fact, a Search Engine Watch survey shows that some meta search services are providing results where more than half of their listings are paid links."

Copernic is still my favorite meta search engine (and it now includes Google) but since it's a desktop app, not a web site, it's often not included in comparisons.