...and people snort at me when I talk about how insecure most home wireless setups are... all you have to do is detect a network (turning off broadcast SSID only stops well behaved devices from seeing it)... check to see if it is "secured"... check the router model, see if the default admin password has changed... check for any known exploits or holes in that router's firmware... check for a client side firewall on each wireless client (which is by far where most setups fail to be secure)...
...then you're in. Run an app like this, grab everything you can, and bolt on down the street. A good hacker can do this in minutes, a whole suburban sidestreet in an hour.
...and the scary part is that there are automated tools for running through this process so even a bare amateur can have reasonable success if he checks enough houses.