Hiring a Programmer and Online Quizing?

Hey am in the process of hiring a developer. However, I want to make sure they are good as they claim to be. As we all know people can get a little big headed at times. That said, what would be the best way to quiz them?

I remember one time I went applied for a job years ago. They put me on this computer and had me take a 30 minute test. I'm wondering if there is something already out there like that for PHP / MySQL developers. That we can install on our server and have them take it?