Call to Compile a List of Social Media Sites

Hello friends!  I want to compile a list of social media websites.  All of them.

We all know the basics – Digg, Mixx, Reddit, Propeller, etc. – but what about the others?  There are probably three hundred trillion of them, give or take, and I would like to compile a complete list.  If you know of any, please post them here in the comments.

Thanks!