This CitiBike Rental Dock uses several different sensors and switches to operate. You are able to rent a bike with your credit card, and once processed the bike is released. The internet interaction is between the machine, and the respective bike dock that releases the bike. When the bike is returned, the dock sensor sees that the bike is returns and the timer stops and the total charge is calculated. All of this is powered by the solar panel on the top of this dock.
This room call device is part directory (on the right) which is no technology, but then when you press a button for the room you are trying to call, a sound and light goes of in the room and that person hits a button which unlocks the door downstairs so that you can come up. There is a timer that only keeps the door unlocked for a brief amount of time, before re-locking the front door, to protect the building.
This door switch is similar to the one that Max and I used in our fortune cookie experiment. It sends a signal to the alarm system, that will not let you set the alarm unless the switch is closed. These are on all of the doors to make sure that the alarm cannot be bypassed.