Interested in finding open wireless access points in a particular neighborhood? WiFiMaps.com collects data gathered by wardrivers all over, and presents them in a searchable (by zip code, for example) database. The results are displayed in a table or overlaid on maps (which are very cool, but worked only intermittently when I visited).
It amazes me (or maybe it shouldn’t) how many completely unprotected access points there are. My Dell TruMobile was set for encryption out of the box, but most hardware isn’t, I guess, and most people don’t make an attempt to secure their access points.