In a recent post to his blog, Vinu Thomas posted about a PHP extension that allows your scripts to directly interact with the serial ports on the web server its running on.
Last month there were at least two inquiries at the Bangalore PHP UG on how to get PHP to communicate with the server's serial port. I didn't think it was possible, but here’s what a quick google search turned up...
Two tools popped up on the radar - the PHP Serial Extension and the PHP Serial Class. Both have their benefits, and both can be used for the same kinds of functionality - one for the Windows side and the other for Linux-ish machines. The first seems to be a bit more flexible in its approach, though.