You don't have to have an iSight to run Freak Show. Firewire DV cameras give great results. You can also use most webcams, and of course Freak Show works with iSight too.
Unlike Photo Booth, Freak Show does not require Quartz Extreme and is a universal binary so it can run on any Mac that runs Tiger. You'll want to use a newer computer if you want smooth video. But even a vintage G4 can be used to capture still photos with Freak Show.
Highly recommended for kids and freaks.