Final Project idea

I want to build a working prototype for the type of social networking site that I wish existed, but doesn't.  The idea is to bring people with common interests together in a way that more closely resembles how we make friends in real life.  Hopefully people will have some fun with it.

From a project requirement standpoint it will include these elements:

1)   authentication and permissions

2)  navigation

3)  forms entry

4)  database

5)  XHTML, JavaScript, PHP, mySQL

6)  the MVC design pattern