Surveillancesaver Alpha0
Michael writes –

Not a real hardware hack but a software hack to public available hardware. SurveillanceSaver is an OS X screen saver that shows about 400 live images from public accessible Axis network cameras. it shows surprising scenes from underwater pool cameras, cows in milking machines to shopping malls and street cameras. you don’t want to stop that screen saver..the instructions about the url retrieving are described on the website. The screen saver is under creative commons license.

SurveillanceSaver alpha 0 – Link.