Adding a webcam

Using VisiCam

VisiCam does perspective correction but take a bit more processing power. https://github.com/t-oster/VisiCam/wiki

Using regular webcam

Stream a regular webcam using MJPG-streamer. http://freecode.com/projects/mjpg-streamer

Using Raspberry PI with camera module

Create a raspistill timelapse to a single file and stream this file using MJPG-streamer. Because the raspistill timelapse has a limited time you have to create a script that keeps restarting it.