I have been playing with my webcam in GNU/Linux, I have found this web where you can find a list of interesting applications you can use with a TV or webcam (everything is Video4Linux). I have tested several of them, the most insteresting for me:

• webcamserver You can make your camera’s stream available through a Java Applet.
• lives You can insert effects in your videos, I have not tested it too much.
• EffecTV Absolutely fantastic, you can add real time effect to your camera image… as I have see you can play with “video loopback” to try to record the result. I have to search more info about vloopback.
• Camorama GNOME app

The only thing I have not been able to do is recording video with a decent program 🙁 Xawtv does not permit me to use a lower resolution, it takes 640×480 and the frame rate is too low for a good video.