How to make a social network?

[Daevid Vincent]

Anyone have some pointers at a HowTo on creating a social network?

Basically I need to show people in your immediate network, and also friends
of your friends, etc... Like the whole 'six degrees of separation' thing.
Ala: myspace, friendster, etc. ad nauseum.

I prefer mySQL and PHP, but I could port from most any code. I guess I'm
mostly interested in the theory of this an how do I set up the tables
properly and what is the magic incantation (JOIN) to get this "chain" of
people.