does anyone know of a free, open source viral invitation system for websites? need one for a site launch that is coming up

something along the lines ofwww.launchrock.com? launchrock is what i want, but it's not an open service yet, just a startup idea

i need a system that: -has invite form -gives tracking url to give out -tracks that url gives credit to orginator in system

anyone know of anything like this that i can get, then modify? not looking for paid services (i know of them, unbounce prefinery etc). probably easy to build but im not a developer, was going to run it by my team next week, but checking pre built channels and am coming up empty

php/mysql if possible

Be pretty easy to write one, but have a look for affiliate systems, there are sure to be pre-built cheap ones.

Here's a drupal invitation module that seems to kind of do what you're wanting. http://drupal.org/project/invite

found one. php sql basedhttps://github.com/JamesChevalier/Launch-Soon