Vent-Miser 

Having central heating is easy and convenient, but not very cost effective. For one thing, you’re heating rooms that are not in use. Most homes do not need every single room to be the same temperature. hat’s where this device comes in handy. The Vent-Miser Programmable Energy Saving Vent saves you money by controlling individual room temperature.

Just program the temperature you would like the room to be and Vent Miser will allow or restrict airflow to keep that specific room at the desired temperature. These electronic vents replace the vents you already have to help regulate airflow, rather then replace your current heating or cooling system.

You can program the battery operated vents for each day of the week if you want, instead of turning them off or on each day. The idea is to save you monthly on heating or cooling bills, one user at Amazon noticed a 30% savings after installing these. Only $26.

Via Slippery Brick