Funny, I clicked through something to a finder map the other day. It was an askward interface, but it was a public wardriving database. Some of the open commercial nodes were listed, but it also showed any detectable node and what it's status was. It was slow, but interesting - and of course I have no idea what the URL was.
Google is your friend:
http://www.openhotspots.net/ http://www.wi-fihotspotlist.com/ http://www.wi-fihotspotlist.com/
There are a lot of re-branded jiwire search engines too:
kcwireless.net used to have a link to a local map on nodedb.com, but they appear to be offline now:
http://www.nodedb.com/ http://www.nodedb.com/unitedstates/ks/kansas_city/?
Someone was asking about setting up an ad-hoc network for a festival this Summer. Contact me off list please - I think I may be working on this already.