demo application suggestions

I am going to be manning a booth on apache at a Linux trade show, and I'm looking for suggestions on a good php app to show off. Seeing as a webserver alone is not too exciting, I thought it would be better off to show off what you can do with the apache platform and some of the modules available. If anyone has any suggestions on any php apps that would impress business types, please let me know. I might as well try and drum up some interest in PHP while I'm there :) -- Chad Cunningham ccunning@math.ohio-state.edu "Well, once again my friend, we find that science is a two-headed beast. One head is nice, it gives us aspirin and other modern conveniences,...but the other head of science is bad! Oh beware the other head of science, Arthur, it bites!"