Would you be interested in a low-tech solution for the high-tech problem of people piggybacking off of your wireless Internet connection? If so, researchers at the University of Tokyo have developed exactly what you need: Anti-WIFI paint.
The researchers discovered that adding an aluminum-iron oxide to paint prevents wireless Internet signals from passing through any walls that are covered with it. What this means is you can paint all of your exterior walls with the specially treated paint and the signal from your wireless router will be contained within the house, preventing neighbors and passers-by from accessing the web via your Internet account (which can lead to all kinds of problems, both technical and legal). But if you plan to consider going this route, you need to understand that anti-WIFI paint blocks ALL radio signals – which means you won’t be able to use your cell phone inside the house either.
A simpler, cheaper and probably more practical solution to the problem is to simply enable the wireless security features already built into your wireless router. But if you want to be absolutely certain that no one can access your wireless connection from outside the home in the event that your router’s security should somehow fail, you can always re-decorate your home with anti-WIFI paint and use a low-tech land-line telephone while at home.