Some time ago I wanted to build a dating website, so I registered obicham-te.com
The time has come! :) My friend and I started to examine what we would need about such a website.
Mainly we will use Mysql <-> XMPP Server <-> PHP driven website
Why XMPP? Because it's something new & interesting & easy to recreate in future.
We've choosen Djabberd (http://www.danga.com/djabberd/ - Perl XMPP server) & Zend Framework for base tools.
Till now I have excellent observations on Zend Framework and these days will start coding a XMPP module.