This is an interesting concept. A Spanish start-up, FON, wants to sell you a cheap wireless router in exchange for providing Internet access to other FON users and subscribers. You also get to use any FON hotspot for free as a bonus for providing service. Residents in San Francisco recently had a change to pick up a free one, even though the $5 price tag isn't a whole lot.
I like this concept of wireless. So many home users would be willing to sign up for it, and it means a cheap build-out and maintenance for the company (who is assuredly hoping to cash in on casual subscribers). There's no exclusive contracts, and presumably the service will be cheap since bandwidth is already paid for by the FON router's owner. In densely-packed areas or ones where homes are close to businesses, this could be a good model for providing universal wireless on the cheap. It kind of reminds me of the whole warchalking idea, but with less hassle.