There is a bewildering array of genealogy-themed social networks on the web, and even debate about what constitutes such a network. According to Cyndi's List:
Social networking for genealogy most often refers to the ability to build, share, and interact with online family trees. However, the breadth or depth of the online tools vary across the board. Some tools also offer other features of social networking such as sharing photos or creating calendars and timelines.Your need may be best met by a site that emphasises one particular aspect, so there's no one size fits all site. Perhaps a general social network site, or a genealogy mailing list such as one of the Rootsweb sites, will best meet your need.
Here is my selection of top sites from Cyndi's social network category sorted according to Alexa ranking.
The Top Five
Israel-based MyHeritage.com claims to be the most popular family network on the web. It operates in 36 languages, 50 million members, over 700 million profiles, 17 million family trees, 103 million photos and 50 employees.
Geni Alexa Rank: 7,498; Compete Rank: 4,016
Based in Los Angeles, California, Geni claims to be the leading collaborative genealogy platform with users from around the world working together to build a single, comprehensive family tree currently containing nearly 50 million ancestors and living users and over 100 million profiles.
Family Link Alexa Rank: 34,888; Compete Rank: 1,946
Provo, Utah based, the company is headed by CEO and Board Chair Paul Allen, a serial genealogy entrepreneur (Ancestry, WorldVitalRecords). It claims to have "60 million users already using the #1 social family network" with 500 million family connections, 20 million monthly active users and 3.6 billion indexed names.
Ranked as the No.1 family website based on market share of visits among all UK websites in a July - December 2010 survey, it currently has over 10 million members worldwide and over 750 million names listed. It is part of Brightsolid, which also boasts Findmypast.co.uk and has the franchise for scotlandspeople.gov.uk.
Efamily, incorporates Famiva
Living Genealogy (beta) Alexa Rank: 2,388,939
My Great Big Family Alexa Rank: 2,661,144; Compete Rank: 987,782