5. Boingomobile: If I'm not mistaken this isn't exactly for locating hotspots, it's a special deal you do with Boingo which (with the help of an application) lets you log in to pay-networks (e.g. T-Mobile, and dozens of others) and pay your nominal Boingo rate instead of having to pay-as-you-go with e.g. credit card. If you use such networks reasonably often then it's presumably much cheaper to get a Boingo contract.

p.s. Yes, look at tabletscene (link in vabgeo's post). And http://tabletschool.blogspot.com/