From Wikipedia: A social network service focuses on building online communities of people who share interests and activities, or who are interested in exploring the interests and activities of others. Most social network services are web based and provide a variety of ways for users to interact, such as e-mail and instant messaging services.

Map of Social Networks around the world

Guides

• Creating your Own Social Network on Ning
• Using Ning Screencast

Examples
from  Mashable's List of Social Networks

• Shelfari - Shelfari is a popular social networking service for book lovers.
• Linkedin - LinkedIn is a professional social networking website for business users, one of the most popular such sites out there. Some aspects of it are free, but many are paid.
• Geni.com - An exciting social networking site enabling members to create their family tree. Although it’s a relatively new site, it has grown tremendously fast, and has hundreds of thousands of users.
• 43 Things - A tagging based social networking site. Users create accounts and list a number of goals or hopes and these are parsed based on similarity to goals of other users.
• Facebook.com - Facebook is a social networking phenomenon connection people with their friends, family and other users with similar interests.
• Half.com - A leading student market place for buying and selling textbooks at discounted prices.
• MySpace.com - MySpace is an interactive social networking website consisting of personal profiles, blogs, groups, photos, music and videos. It’s currently the biggest social networking site out there.
• RateMyProfessor.com - RateMyProfessor connects students aspiring to study similar courses by assisting each other.
• WAYN - A social networking website uniting world wide travelers.
• Seesmic - Video based social networking / microblogging mashup
• YouthVoices - High School aged network to encourage student writing
• Ning- Build your own social network 
  
  EFL / CALL Related
  
  Nings
• EFLClassroom 2.0
• Classroom2.0
• EFL University
• Second Life English
• EFL Nng Search
  
  Webheads
  
• Webheads.info ,  WebheadsinAction.org , Yahoo Group , Blogs
  
  Other
• Live Mocha
• ESLCafe.com Forums

Microblogging

• Twitter
• Pownce
• Jaiku
• Plurk
  
  Multi-posting tools
• Hello.txt
• Ping.fm
  
  Guides
• 10 Steps for Twitter Beginners
• What is Twitter? (Sue Waters)
• Mashable's 140+ Twitter Tools
• http://search.twitter.com/
• http://election.twitter.com/

Resources

• Growing Up Online - PBS Frontline
• Learning From a Native Speaker, Without Leaving Home
• One Click From Danger
• Social Network Sites: Definition, History and Scholarship (Danah Boyd & Nicole Ellison)
• The Value of Social Networks (David Warlick)
• What are Kids Doing On Facebook, MySpace and Other Social Networking
• Teens, Privacy and Online Social Networks (PEW/Internet)
• The Semantic Social Network (Stephen Downes, 2004)
• Social Networking Sites: A Parent's Guide (OnGuard Online)

 Task:  Register at Ning, Twitter, and any other social networking sites of interest.  (use a pseudonym if you wish).  After signing in to Twitter, go to http://twiter.com/jefflebow and 'follow' him.  During this upcoming week, try to use social networks to gather information and connections related to your areas of CALL interest (or any other areas of interest). Post if you can, lurk if you must.  Post about your experiences in this week's reflection.