If you've got an iSight camera for your Mac, you may be interested in trying the open source project, Gawker.  It allows you to create time-lapse movies of whatever the camera is pointed at.  You can even grab 'feeds' from other iSights on your network, using Apple's Bonjour networking.  Combine various feeds to do a multi-view time lapse from two angles, etc.  Seems like a fun thing to try - though I don't know how useful it is.  I'll have to test it out and see.  If you've tried it and have some thoughts, please share!  Course if your iSight is built in - as it is with the new Intel Macs - we probably won't care to see time lapse of you coding or something.  Check out the project website for some example movies - the one of ice melting is pretty cool actually.