We have taken a sample of nine of these companies - Ning, KickApps, CrowdVine, GoingOn, CollectiveX, Me.com, PeopleAggregator, Haystack, and ONEsite - all of which provide free baseline services, and reviewed them individually below
Ping.fm is a simple service that cuts out the middle man when it comes to posting to your social services such as Facebook, Twitter, Jaiku, Tumblr and Pownce with more being added soon.
M. Nentwich. ita-Manuskript, ita-09-02. Institut für Technikfolgen-Abschätzung an der Österreichischen Akademie der Wissenschaften, Wien, (November 2009)
A. Budura, S. Michel, P. Cudré-Mauroux, and K. Aberer. 6th Annual European Semantic Web Conference (ESWC2009), volume 5554 of Lecture Notes in Computer Science, page 608-622. Springer, (June 2009)