Pretty cool! I have done some of the same stuff myself only using php for frontend and Visual Basic for backend. This was back when I interfaced with my computers printerport (not yet knowing about the Arduino :P). Kinda cool to have a website with live logs for my door and a couple of other things, controllable christmaslights and a few leds and a webcam, and see friends in California and the Netherlands control physical stuff in my room. ^^
A little off topic, but I have also made a couple of incarnations of a web-controllable mediaplayer also using VB as backend and php as frontend. It was kinda annoying, though very cool, to have both those projects running at the same time. Music playing (and always the worst possible music they could find on my computer ::)), lights going on and off..
But I think just about the coolest part of that project was the mini version of the online controlpanel I made for access with my cellphone.
Any chance you could post your source? I'd like to modify this for a web controlled RC Car, and I'm much more familiar with PHP than CGI.