that it is a matter of expanding your knowledge of networks and wireless connectivity, as well as the desire to hack networks around you. For example, I live in an apartment complex and there are loads of WEP protected networks around (they all should be at least WPA). With the right network card, it would be extremely easy to commandeer their network completely anonymously. I don't think it's ethical and I wouldn't use it as my primary internet, but if I needed the bandwidth...

It also demonstrates how weak wifi security is, but at the same I'm in England and free wifi is still a bit scarce. Other than that, you have to be lucky that some person is not protecting their connection.

KisMAC is also an excellent search finder for networks, whether they are protected or not and the strength of their signal. In that sense it's really handy, but it's also a hacker tool.