IT Admin groups on social networking sites

Social networking sites are on the rise, that much is apparent. Tom Anderson sold myspace.com for $580 million dollars. Current estimates are guessing over 140 million users on Facebook. And before you think that social networks are just for kids, Linked In hosts 30 million profiles of experienced professionals who are looking to network with others. Clearly, these sites are tools which can be used to learn and grow in a professional capacity.

I've had my LinkedIn account for a long time, and initially I resisted the others. Eventually I succumbed to Facebook, then myspace, mostly due to peer pressure. Since I have accounts on those three networks, I figured I'd check to see if there were any groups put together by IT administrators. And how.

Most of these groups feature discussions on various topics that you might find interesting. Check them out,and let me know what you think.

LinkedIn
IT Management
System Administrator (Mac, Win, and Linux)
System Administrators
Nagios Administrators

Facebook
Unix Sysadmin
Linux Administrators
Cisco Systems
Appreciate your sysadmin
*NIX
Network/Security/System Administrators
System Administrator Appreciation Day

MySpace
Sysadmin Superstars
Network Admins / Engineers / System Specialists
Computer / Network Administrators
Sysadmins
Network / Sysadmin / Comptechs
Network Engineers

If you know of any other social networking sites (or other types) that you'd recommend, let us know in the comments. I'm always looking for other sources of information, and I know lots of other people are too.

[EDIT]
Talk about coincidence. I wrote this last night and scheduled it for this morning for 8:30am. Before it could go live, Dru posted a link to some BSD Certification groups created on LinkedIn. Funny how things happen sometimes :-)