On 9Lessons.info today there's a tutorial posted by Srinivas Tamada about creating a simple "tag my friends" system (like Facebook's) with PHP, jQuery and a bit of Ajax magic.
I received a request from my reader that asked to me how to implement Facebook like tag friends in your status or update box. It is great feature to adding friends start with @ symbol. I had tried this with Jquery, Ajax and PHP, it's simple just collaboration of my previous posts.
If you want to skip to the good part, there's a demo and code download otherwise you can follow along with his code that creates a database table, includes the HTML for the interface, a backend PHP script to connect to and some CSS to make it all look a bit nicer.