Mindset
Scoble pointed out an interesting search engine project called Mindset which was done by Yahoo. It can weight your search by commercial and non-commercial results .
A Yahoo! Research Labs demo that applies a new twist on search that uses machine learning technology to give you a choice: View Yahoo! Search results sorted according to whether they are more commercial or more informational (i.e., from academic, non-commercial, or research-oriented sources).
http://mindset.research.yahoo.com/