Without going into too much detail, I current have a web interface that allows me to access the lighting in my home. The controller only has a serial port. My system is a linux machine. In my case, I have a 'C' program that knows how to talk to the lighting controller. The program can be executed from the command line. To make it web-enabled, I wrote a simple perl script that translates clicks on the web page into the proper arguments for the command line program and then executes it. I dont have a webcam, but others that I have seen simply continuosly overwrite a file on their drive and then serve the most current file whenever the browser requests it.