On May 11 Nielsen//NetRatings released their press release on the top social networking sites for the US [pdf].

“Social networking sites are the reality television of the Internet,” said Jon Gibs, senior director of media, Nielsen//NetRatings.

Top 10 Social Networking Sites for April 2006 (U.S., Home and Work)
1. MySpace
2. Blogger
3. Classmates Online
4. YouTube
5. MSN Groups
6. AOL Hometown
7. Yahoo! Groups
8. MSN Spaces
9. Six Apart TypePad
10. Xanga.com

In summary, 45% of of web users are reached through these sites. Good summary of some relevant sites, but I wouldn’t call them all “social networking” sites. What isn’t social on the web? They’re a mix of sites that try to encourage socialising, sites that facilitate self-publication, sites that facilitate finding each other, sites that facilitate grouping according to interests…a big mix which I think is silly to bunch together. I guess the list is more for advertisers to reach consumers, it is about sites that have the greatest reach, sites that people gravitate too. Anyway, quick stat and quick rant over.