Indigo
Scott writes –

I mentioned last week that I’ve been working on building sort of a lightweight home security system for my house so my 4-year-old daughter won’t be able to sneak out of the house again.

I spent about a day researching possible solutions, to see if there was something simple that I could buy that would make me happy, and I couldn’t find anything on the market that was cheap and would tell me which of my 6 exterior doors had been opened loudly enough to hear from across the house. There’s no point in putting a door buzzer on the basement door if you can’t hear it from the master bedroom. The only solutions that I found were from professional alarm companies, and they probably would have charged me a couple thousand for installation plus $30-$50 per month for monitoring. I’m just not willing to pay that much, and it’s not really what I was looking for-it’s gross overkill for my problem.

So, I decided to build it myself….

Lightweight Home Security with Indigo and Asterisk, thanks Surj! Link.