Reasonably doable. an RFID chip in the key would identify the holer of the key, likely.

How would the children feel about this?

They'd do the same thing I'd do. Put the key in the front door and then go back out. Moronic parents believe they can solve these problems by throwing money and technology at them. Nothing will guarantee the integrity of your child but how you raise them.

Oh, on a secondary note, as soon as I got pissed I would put my key in and out a couple hundred times and leave a couple hundred E-mails in your inbox.

Aahh, to be a kid again.

While a key/lock trigger might be tough, the concept has an appeal. I have asked my daughters to send me an email when they get home, or to call me.

Funny, MYSPACE takes a lot of heat for opening dangerous doors... but it can also be a honeypot where I can see when my youngest got home, as homework seems to come at some time after she checks her e-social tool (as I call it).

So, instead of building a lock/ email trap, build a lure & get to the same outcome. I say get them into myspace, then watch them as needed (and they may need more than you want to think).

Good idea, even if the implementation might be a bit different than your first impulse.

I like classicsat's idea. If keys came with RFID chips embedded in them then they could also be serialized; opening many doors for creative applications.

The RFID could be used to trigger the porchlight before getting to the door.

The RFID could configure your computer when setting down to your preferences, regardless of whose computer you sit in front of, so long as an internet connection is available and you have administrative permissions. The Systems Administrator could potentially improve their productivity in various ways.

The RFID could set house temperature preferences, music, lighting, ....

The RFID in the key could automatically enable and disable building alarms while moving from room to room in businesses. Thereby locking down sections of the business as the security guard moves from room to room.

The RFID in the key could track the performance of security guards automatically.

The RFID in the key could allow the blind to better locate door knobs by a weak buzzer sounding as they approach the door.

This is a great idea classicsat! And you too dgumbs! Your idea promoted other ideas.