Some new social blogging sites are below - one note since the Summer is ramping up around here with vacations and trips - we'll work on bringing back the Social Thursday blog in August.

These are from the March 2007 Issue of Business 2.0.

http://www.stumbleupon.com/

One use for that would be to download the toolbar and then "Stumble Upon" your own site(s).

http://www.slide.com/

http://www.bebo.com/
Similar to MySpace.

http://wwwl.meebo.com/
A way to sign into all of your IMs.

http://www.wikia.com/wiki/Wikia
If your area of expertise doesn't have a Wiki then why not build one.