The battery-powered Vent-Miser features a clock that opens and closes the vents at programmable intervals, completely independent of your thermostat's settings. So if your A/C doesn't need to keep your guest room cool on weekdays or if you only need to heat your bedroom at night, the Vent-Miser can automate this process for you, possibly saving you a few bucks in the process.

At about $25 a pop, the vents definitely lean towards investment rather than instant payoff, but they're a neat idea if you live in a house with crummy HVAC. [Amazon via OhGizmo!]

The Light + Air door is designed to enhance cross ventilation without giving up any security or light. Slide a lever to the right, and the circular openings are exposed—not big enough for anyone to stick a hand in and open the door, but large enough to let the sunshine and fresh air pass through.

Who wants to live without air-conditioning if there is poor ventilation? The Light + Air Door design concept is an answer to that pressing and probably upcoming problem: how do you stay comfortable when it costs $2000 a month to keep your abode cool? Just don't install this door if you live in a submarine. – Charlie White

Design Concept Page [Seven O2 Design, via treehugger]