Here are the 16 Most Popular Social Networking Websitess as derived from our eBizMBA Rank which is an average of each website's Alexa Global Traffic Rank, and U.S. Traffic Rank from both Compete and Quantcast. "*#*" Denotes an estimated Quantcast rank for websites yet to be Quantified.

1 | Facebook
2 - eBizMBA Rank | 550,000,000 - Estimated Unique Monthly Visitors | 3 - Compete Rank | 2 - Quantcast Rank | 2 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

2 | MySpace
19 - eBizMBA Rank | 90,500,000 - Estimated Unique Monthly Visitors | 10 - Compete Rank | 17 - Quantcast Rank | 29 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

3 | twitter
19 - eBizMBA Rank | 89,800,000 - Estimated Unique Monthly Visitors | 26 - Compete Rank | 19 - Quantcast Rank | 11 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

4 | Linkedin
47 - eBizMBA Rank | 50,000,000 - Estimated Unique Monthly Visitors | 61 - Compete Rank | 50 - Quantcast Rank | 29 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

5 | Ning
143 - eBizMBA Rank | 42,000,000 - Estimated Unique Monthly Visitors | 180 - Compete Rank | 120 - Quantcast Rank | 128 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

6 | Tagged
225 - eBizMBA Rank | 30,000,000 - Estimated Unique Monthly Visitors | 382 - Compete Rank | 151 - Quantcast Rank | 141 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

7 | classmates
228 - eBizMBA Rank | 29,000,000 - Estimated Unique Monthly Visitors | 487 - Compete Rank | *425* - Quantcast Rank | 969 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

8 | hi5
479 - eBizMBA Rank | 27,000,000 - Estimated Unique Monthly Visitors | 983 - Compete Rank | 392 - Quantcast Rank | 62 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

9 | myyearbook
617 - eBizMBA Rank | 12,000,000 - Estimated Unique Monthly Visitors | 522 - Compete Rank | 293 - Quantcast Rank | 1,036 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

10 | Meetup
635 - eBizMBA Rank | 8,000,000 - Estimated Unique Monthly Visitors | 644 - Compete Rank | 732 - Quantcast Rank | 528 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

11 | bebo
655 - eBizMBA Rank | 7,000,000 - Estimated Unique Monthly Visitors | 944 - Compete Rank | 434 - Quantcast Rank | 588 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

12 | mylife
865 - eBizMBA Rank | 6,000,000 - Estimated Unique Monthly Visitors | 118 - Compete Rank | 688 - Quantcast Rank | 1,789 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

13 | friendster
955 - eBizMBA Rank | 5,000,000 - Estimated Unique Monthly Visitors | 1,920 - Compete Rank | 643 - Quantcast Rank | 301 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

14 | myHeritage
1,097 - eBizMBA Rank | 4,800,000 - Estimated Unique Monthly Visitors | 707 - Compete Rank | 595 - Quantcast Rank | 1,989 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

15 | Multiply
1,136 - eBizMBA Rank | 4,600,000 - Estimated Unique Monthly Visitors | 2,446 - Compete Rank | 677 - Quantcast Rank | 285 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA

*16* | orkut
1,303 - eBizMBA Rank | 4,500,000 - Estimated Unique Monthly Visitors | 2,219 - Compete Rank | *1,630* - Quantcast Rank | 59 - Alexa Rank.
Most Popular Social Networking Websitess | Updated 10/05/2010 | eBizMBA