I stumbled across this site while researching API websites. 
OpenWifiSpots.com will map the available free wifi sites on Google maps. I inputted downtown Chicago and the map below was displayed. The site also can breakdown the search in several categories and includes travel guides.
January 10th, 2008 at 6:48 pm
Nice tool. Pity it’s only for US spots.
January 11th, 2008 at 5:03 am
extremely useful if your in a big city. Darn if my city listed zero. I am going to San Francisco and there are ton listed so that will help.
Thanks for the good resource.
January 12th, 2008 at 11:06 pm
I will look for an international site