As I noted in the listing of Wi-Fi directories, Wi-Fi-Freespot Directory, http://www.wififreespot.com, focuses on free hotspots. This is a good starting place if you are looking for no-cost Wi-Fi public access. It is also worth noting that some of the big telecom providers give free Wi-Fi access to users subscribing to some of their other services.
Most of the free hotspots fall into one of three categories:
Provided by a business in the hope of drawing traffic
Provided by a library as a public service (see the following discussion)
Provided by a local community (see the following discussion)
It's really worth browsing Wi-Fi-Freespot to see what local businesses you can find that provide free Wi-Fi. You'll probably be absolutely amazed at how many there are. (I know; I know: My community, Berkeley, California, is not typical of anything, but there are literally hundreds here.)
Many public libraries provide Wi-Fi free access to the public (or at least to members of the community who have registered for a library card). The Wireless Librarian has a great directory of Wi-Fi availability in libraries: http://people.morrisville.edu/~drewwe/wireless/wirelesslibraries.htm.
Wireless Communities, http://wiki.personaltelco.net/index.cgi/WirelessCommunities, provides information about community-maintained Wi-Fi hotspots all over the world. This is worth checking out. You'll be surprised at how many community-based providers of free Wi-Fi networks there are, as well as the passion and commitment of the people and communities that provide this free public service.
Many municipalities, such as Austin, Texas and Philadelphia, Pennsylvania, are rushing to put up municipal Wi-Fi hotspot networks. As these go up, here are a few sample wireless communities of relatively long standing:
Bay Area Wireless Users Group (BAWUG) is one of the pioneering free Wi-Fi organizations. In addition to BAWUG's other activities, the group maintains a number of free hotspots centered around the Presidio in San Francisco. http://www.bawug.org
Detroit Wireless Project (DWP) helps maintain a number of free hotspots in downtown Detroit. http://www.dwp.org
Personal Telco Project (PTP) has more than 100 hotspots in Portland, Oregon, and has contributed to Portland being named the "hottest" cityor city with the most hotspotsin the United States for several years running. http://www.personaltelco.net/static/index.html
Seattle Wireless, in addition to supported hotspots around the Seattle area, has pioneered an alternative public backbone for wireless networking. http://www.seattlewireless.net
Wi-Fi to the Max: Take Your Mobile Computer to School!
Almost every university and college in the United States offers free Wi-Fi access to its students. This access is not, in most cases, available to the general public. However, if you are attending college, or plan to start next year, it is very likely that your school will provide convenient Wi-Fi access for you. You should check with your school to learn the details of the Wi-Fi access provided and plan to bring your laptop.
In addition, it is often possible to arrange for guest access to a university or college wireless network, particularly if you will be using it for scholarly research.