myspace: 51,441 (thousands, May 2006) classmates.com: 14,792 facebook.com: 14,069 youtube.com: 12,669 msn spaces: 9,566 xanga.com: 7,146 flickr.com: 5,163 yahoo 360: 4,936 livejournal: 3,904 myyearbook.com: 3,048