Home Made Alarm Systems?
screwBrinks! asks: "I would like to begin a new project to do during those long and boring weekends. I thought about creating an alarm system in my apartment which would be connected to my computer. Then, if there is any intrusion, it would page me or phone me. I also want to be able to see a live report from the web and some other goodies. I have no problem doing the software part, but I don't have much experience with building hardware. Have any of you ever built such a system? If so, what would be your recommendation? I know much of this may already exist prebuilt, but I really would like to make as much of it as I can, for fun. I have no problem against using prebuilt infrared detectors, prebuilt door contacts, and the like as long as they aren't X-10 products."
I found this a while ago. This connects to your printer port and supports 5 zones. The electronic hardware is quite easy to build (I've built simmalar things). You could also modify it to provide home automation.