Omnivorous Surfer

Whether on vacation or just out of town...okay, or even in town...it can sometimes be very useful to find Wi-Fi hotspots. Of course, you can turn your laptop/PDA on and wait for it show a connection, or you can buy wireless signal finder, or...
... if you are able and willing to look for spots ahead of time, there are several websites that provide listings. One such site is JiWire. Simply put in a city or ZIP code and it will give you a listing along with an option to view an area map or to view a map of or directions to any of the locations. For each location, the protocols served (802.11b, 802.11g) and connections options are included. Some use Wi-Fi networks such as Boingo and iPass as well as free options.
You can access JiWire's database using CNET's  Hotspot Zone, which highlights the free access sites by using red text for the word "FREE, making them easier to spot.
You can also focus your search on free access sites by using Wi-Fi Free Spot, though you'll have to do the search through a city's lising after finding the city and state. The site also offers specialty listing pages for companies with multiple locations, airports, hotels, RV parks, and vacation rental properties, etc.
PC World has a Mobile Computing blog entry , "How to Find Hotspots," if you're interested in reading that. It includes several other sites along with the pros and cons of each.
To learn much more about Wi-Fi hotspots and using them, see about.com's Finding and Using Wi-Fi Hot Spots