For social networking specifically for educators, please see Social Networking for Educators.

There are lots of non-education network sites where teachers are also posting information. Many teachers want to connect through their hobbies, schools, side businesses or consultant work, etc. So here are a few sites that you might want to consider:

MySpace - not recommend for education because it lacks privacy features

Facebook - some schools/districts block Facebook because students frequently post inappropriate messages or pictures. There are privacy settings that provide a false sense of security because anyone can cut and paste pictures to anywhere on the internet -- including the friends have access to your Facebook page!  That said, Facebook can also be a good way to contact students with reminders etc. and some classes have their own groups on Facebook. Schools also use Facebook to organize events.

http://thewallmachine.com/ is a clever tool for creating Fake Facebook Wals. A number of teachers have used it for education applications, eg. creating profiles or streams based on literature or historic figures.

LinkedIn - this site is huge among business people and anyone offering or looking for services. It is also good for connecting up with former schoolmates, etc.

Twiducate - a social network for the classroom.