So if you are paranoid you might want to hop on over to Hack-A-Day to see the GSM based motion sensor alarm they’ve recently posted. Essentially what happens is when the alarm is tripped, during a certain time period, it calls someone.
Now who that someone is would be up to you, but I would recommend the police. At the very least you yourself should be on the call list.
It uses a GSM phone (probably a recycled one or one of the prepaid disposable ones), a motion sensor, and a basicx24 controller board. It is a bit big, but that probably wouldn’t be too daunting after its been hidden. You could probably shed some weight and size by removing a lot of the extraneous stuff from the motion sensor. It’s a pretty great idea though and would certainly be nifty for several applications.
Gsm alarm [via hackaday]