WiGLE.net is a submission-based catalog of wireless networks. Submissions are not paired with actual people; rather name/password identities which people use to associate their data. It's basically a "gee isn't this neat" engine for learning about the spread of wireless computer usage.
WiGLE concerns itself entirely with 802.11b networks right now, since it's REALLY hard to deal with cellular networks, 802.11a is so hard to catch, and everything else is so small-share. 802.11b appears to be experiencing an explosive growth, and it's neat to see it cover cities.
More information is available here.