On an educated guess, I peeked into the Photo Booth package on my new MacBook (which I've named 'lunchbox' after my friend derisively termed it as such. I'd named it 'big-iron', but was feeling uncomfortably prosaic. How obvious a bit of irony is that?) and found what I'd hoped for: a Quartz Composer file. When I dragged a copy of it to my desktop, I was surprised to see that the finder treated the file's preview just like it would a Quicktime file:
When I click the play button, there it is, sucking in a live feed through the iSight and running it's sweet little matrix effects on my head!
Why is this interesting or fun? Well, if you haven't fired up Quartz Composer, it's a delightful tool box of graphical object programming. You "wire" together modules to create visual processing effects. There's a wide range of sources (images, text files, http sources, image capture devices such as the iSight) and a bunch of filters (blurs, edge overlays, swirling psychedelics, etc). You can create macros for reusability and there's programming primitives like loops and conditionals.
Of course, like any graphical "programming" environment, it can be sort of ponderous to deal with. All that clicking, hunting for this setting or that, looking in inspector windows. On the other hand, it's a hell of a lot of fun.