MySpace v. Facebook-What are the numbers of unique visitors?

http://www.techcrunch.com/2008/06/12/facebook-no-longer-the-second-largest-social-network/

Statistics on World Wide Usage of Internet

Remember that people who are not online may have many reasons why they are not:

http://www.etcnewmedia.com/review/default.asp?SectionID=10&OverviewID=3 

http://www.internetworldstats.com/stats.htm