If you miss your job as a security officer at the local mall, we've found the screen saver for you.

We're watching you, who ever you are.
Using over 600 network surveillance cameras worldwide, Michael Zoellner has created a live feed screen saver. The eerily hypnotic images will keep you focused on the going's on of hundreds of live feeds. That is, until you see yourself.
While it worked on my machine, Peeping Toms should use caution when using the software, it's still in alpha.
Links:
[1] http://i.document.m05.de/?p=418
[2] http://www.boingboing.net/2007/11/05/screensaver-displays.html
[3] http://www.maclife.com/article/can_screen_savers_be_saved_as_quicktime_movies
[4] http://www.maclife.com/article/can_i_make_a_screen_saver_out_of_my_own_video
[5] http://www.maclife.com/article/defcon_globe_screen_saver