Something is beeping in my house intermittently. It is not the smoke or carbon monoxide detectors!
A once per hour beep sounds a lot like a low battery indicator -- what else do you have running on batteries around the house?


Some things to check:


Internet/Phone - specifically in my area, Verizon FIOS often has a battery backup so that phones don't go out when the power goes out in order to better simulate POTS Actually, in many recent FIOS installations they haven't bothered because people wouldn't bother to replace the batteries.
Burglar Alarm
UPS - Typically attached to a computer