1) Exlporation. Residential areas will only have family type networks, that should be obvious. Try an urban area, it should yield more interesting results.
2) Like Gizmo said, change your ESSID regularly. It takes a program like airsnort 10,000 packets to get your key. That takes a little while so if your extremely paranoid you can change your key daily, rotate them. Something that I do that helps is that I have my wireless router outside of my LAN so none of my internal servers are accesible from the wifi network (except from the same means that they are accessible to the rest of the internet).