Most popular Web 2.0 service: social networking
•Social networking sites sell banner ads, user preference information, and music, videos and e-books
•Social shopping sites
•Swap shopping ideas with friends (Kaboodle, ThisNext)
•Wisdom of crowds/crowdsourcing
•Large numbers of people can make better decisions about topics and products than a single person
•Prediction markets:
•Peer-to-peer betting markets on specific outcomes (elections, sales figures, designs for new products