Haven't used it but take a look at this:
http://highlightcam.com/
This app will record and post to twitter or youtube & more:
http://www.yoics.com/2009/05/tweet-your-webcam/
This motion detect app that takes stills..(scroll the bottom of the page to: Motion Detection 1.02)
http://www.hiren.info/downloads/freeware-tools/6
and you could also try yawcam:
http://www.yawcam.com/