I need to get one of these. From Gadgetry Blog:
The Grand Daddy of Ghost meters, the TriField Natural EM Meter ($179) ignores power sources and appliances and has a built-in tone to alert you of spooky activity. It also comes with instructions on how to stay alive (sorry, I added this bit for effect!). The gizmo has a radio frequency range from 100KHz all the way up to 2.5GHz - if that means anything to you - so you can also check for leaky microwave ovens, monitor cellular phone radiation, and look for RF-based surveillance 'bugs'.
See, it's multifunctional.