Bill Drew's list of Wi-Fi-enabled libraries: Bill is the associate librarian, systems and references, at SUNY Morrisville College Library, and he's assembled a list divided geographically of libraries that offer Wi-Fi -- typically to their patrons as well as for staff. He's accepting submissions to increase the list!
Combine this list with Wi-Fi Free Spot and a list of community networks (I can't find a good one at the moment!) and you have a pretty good way to target legitimate places to get free access while traveling around especially if you're traveling by car with a good map, GPS, or navigation system.