Random Image PHP

[Matt G]

I need to create a random image to use as a avatar for the forums i participate on. Does anyone know of a php script which will allow me to point to

http://www.gamersboards.com/mattsavatar/avatar.php
and get the random image

i already have a folder full of jpgs but id rather have it were it uses gifs, jpgs and pngs.

Thanks a bunch
MattG