[Novalug] Open Source Alarm?

[Nick Danger]

I had an alarm guy come to the house last night and look over some of my 
options. The entire time I kept thinking that other then the 24 hr 
monitoring they do (the service part), I can do the hardware part easily 
with a SBC that has a decent digital I/O board on it. That got me 
searching google for linux based alarms. Or even non-linux based alarms 
that I can at least interface with. Certain things they are not going to 
monitor (water in basement, power outage...) and thats easy enough to do 
with home automation, but what about the alarm part?

Anyone seen anything like this?