Best Social network opensource application

Hello,
I am thinking to build my own social networking site. But don't know which script is opensource and the best on the web. And which is some what facebook type

Any advice?

 

Twitter is the best way for social networking.

 

Basically, i'm thinking of buying the script.
I need suggestions who have experience on this field.

 

Here is one that looked pretty interesting.

http://www.socialgo.com/

 

Elgg is pretty good, easy to use / install and has a growing community, well worth taking a look at it. If you want to write your own plugins/themes it can be a bit clunky to get used too; everything works with views and you need to build your own as you need them.

http://elgg.org/