Every since MySpace, social networks have begun to spring up overnight.  Many of them to connect with your friends in different ways.  An interesting trend has been the creation of social networks for MMO’s and Virtual Worlds.  Many people have fallen in love with Facebook, it is a cleaner, more personalized way to communicate with others through a Social Network platform (even though there are major privacy concerns.)  There is a strong Second Life community on Facebook but it has a policy for closing profiles of people who are not real identities.  While Facebook and MySpace are great ways to communicate with your virtual friends, there are other virtual world social networks that all attempt to connect people through virtual means.  Here’s a list of a few with pro’s and con’s for each one.

• Avatars United: Dedicated to many MMOG’s and Virtual Worlds but has an interesting premise.  One login for as many virtual world personalities that you have – you can add alts from other games or Virtual Worlds and connect with others. (Thanks Vint Faulken for pointing this one out)
• Koinup: A social network dedicated to sharing art, machinima and virtual world stories.  Koinup seems to have been dominated by Second Lifers but also includes TSO, WoW, IMVU, There, and ySide.  While great, I’m not fond of it’s design (and google ads everywhere).
• Myrl.com: A virtual world social network that is in invitation beta mode.  It looks interesting, but includes both Second Life and There and “cross world” opportunities.  Very AJAX and interesting. (Added: April 17th, 2008)
• Rezzed.net: One of the smaller Second Life specific social networks.  Rezzed.net includes a shoutbox, event listings, and a Status update.
• SLProfiles: The oldest Second Life social network.
• SLScout: Ran by the NingID system, SLScout seems the most AJAX of all the social networks here.  I like it’s ease of use and single login (to as many social networks on the NingID system)
• SLUniverse: Although not a social network in definition, this community site is one of the longest running Second Life community sites.  It’s powered by vBulliten, the PHP forum program, but does deserve a mention here.

If you don’t want to sign up for a billion more social networks, there are many other ways to connect with your friends through already existing ones:

• Second Life Link: Although not a social network, a way to connect with other social network-ies through Facebook.  A nice application and already builds on the popular Facebook platform.
• Second Life Flickr Group: This is a collection of pictures of Second Life on Flickr.

I’ll do my best to keep this list current. (Last Update: April 17th, 2008)