U.S. 2010 digital revenue: $330 million
Snapshot: QuinStreet is where many financial services and education companies go for online sales leads (it has a smaller presence supplying leads to B2B, healthcare and home-services firms). The publicly traded company also happens to hold the record for the highest price ever paid for a domain: $16 million for Insure.com and its related assets in 2009.
Key digital move in 2010: The company went public in early 2010, raising $140 million. It used the proceeds to buy several other sites, including Insurance.com and CarInsurance.com.
How we generated our estimate: QuinStreet is publicly traded. The vast majority of its sales come from the U.S.