Parallel are interesting indeed, but for people who do not know more about SecondLife we must indicate that it is provide a complex interaction between users including vast wiki, inner scripting language and advanced API.
Links:
http://wiki.secondlife.com/wiki/Main_Page
http://wiki.secondlife.com/wiki/LSL_Portal
http://wiki.secondlife.com/wiki/APIs_and_Web_Services_Portal

P.S. SecondLife is great, but the truth is you can only have one full life.