It's not free but worth reading about
http://www.boingo.com/retail/
FIOS users can use Boingo without signing up. USE your Verizon WIFI id and password (NOT REGULAR ID AND NOT ROUTER ID). Not sure how many locations are available that way.
You need to signon up once and setup a userid and password (not the same as your regular verizon id and password). Start at http://www.verizon.com/wifi
If you did setup you can ask what your id and/or password from pages hung off that page.