[dba-Tech] Website dev question

Hey,

I have a friend that has a website.  He is looking for a solution that can
be added (he is not a developer, but he contracts with some that could apply
the stuff) that would give private messaging and a friends list type
functionality that would run against a MySQL database.  

Anyone have any information on anything like the above?  I am a
client-server developer but know little about web dev other than web
services.

Thanks,
Bobby