I don't have any recommendations on maps, but just some general places that you might look for free Wi-Fi. I live in a college town of about 25,000 and Wi-Fi is available all over the place. If you are running NetStumbler while you drive around, you will probably be amazed at what you can pickup. If you don't want to leave your car, you will probably find access outside hotels, espresso shops/outdoor cafe areas, and the Public Library (not to mention outside schools). Newer restaurants are adding Wi-Fi to attract the business crowd. The university has their "official" access points locked down with a valid university log-on being required, but unofficial (rogue) access points probably still abound, particularly around residence halls.
These days, you can probably pick up open access points in just about any neighborhood and most people don't know enough to "lock them down" or even turn on WEP encryption. I leave the ethical considerations to the individual, but I personally liken it to someone having an overly powerful sprinkler system on. How unethical is it to catch a cup of water from the curb?
Picking up an open point is probably less time consuming than finding a map and locating a specific location - in my opinion. Those wanting to learn more about detecting open access points can simply do a Google search on "wardriving" (adding the word "tutorial" may narrow the search).
Darren Addy
Kearney, NE