Google bought this mobile-payment platform in August 2010. Onlookers assumed it would be part of Google's social networking efforts. In fact, the team was put to work on in-app payments, and earlier this month Google said it would shut down the Jambool Social Gold service in May, and replace it with its own in-app payment system.
#13: Invite Media ad platform, $81 million
Google bought this ad technology company last June, making its 24-year-old founder Nat Turner a young millionaire. Invite is a demand-side platform (DSP), which helps ad buyers place their wares on ad exchanges, and hasn't yet been integrated into Google's other ad-buying products. Google recently wrote a blog post explaining when advertisers should use Invite versus the Google Display Network.