You could use them for occupancy sensing or connect them up to a wireless alarm system. Most wireless systems allow for at least 2 wired sensors, plus they sometimes have modules to accept several wired sensors. I have successfully used door/window sensors which often have a pair of terminals to connect a wired sensor to them. The only problem is supplying the sensors with power. But as all the sensor cabling should be going back to a central unit then this shouldn't be too much of a problem, as you could use a single 12V dc supply (but check to make sure its 12V you need).