Are You Looking for Statistics about Social Networking Sites (e.g., Facebook, Twitter, LinkedIn, Myspace, etc)?

Here is a nice collection of usage statistics on social networking sites, including Facebook, Twitter, LinkedIn, and Myspace.

The social networking applications are really interesting from an information seeking and from an advertising perspective.

I am presenting research on using social networks and technology (specifically micro-blogging on Twitter) at the CHI 2009 Workshop Social Mediating Technologies, along with my co-authors for the research paper, Abdur Chowdhury, Mimi Zhang, and Kate Sobel.