- Security cameras
- video cameras attached to a central viewing location, so that security guards (or police in some cases) can monitor many places at the same time. It is said that the highest concentration of security cameras is in Las Vegas, NV.
In the porn world, security cameras provide a number of great chances to produce interesting content. The concept is that with security cameras in places like elevators, gym locker rooms, hallways, dorms, and just about any other place, you have many ways to get things caught on camera.
In sites like Voyeurdorm and similar, there are cameras all over the house, and you can become a member and peep in on the housemates 24 hours per day.