WiFi is hackable, plain and simple. At the very least, someone near your network can steal the bandwidth and use it for all types of illegal internet activity. One partial solution is DefendAir interior paint from ForceField Wireless
. When you apply this on a wall, it can dampen the amount of WiFi, WiMax, or Bluetooth frequencies escaping into outside rooms, homes, or pesky spies parked outside in a black van. It works, though you're going to need at least a couple coats for it to be really effective. Problem is, it's a little expensive, even at the current sale price
of $69 a gallon.