Since I posted this idea I discovered that there are several projects trying to do exactly this:
[Originally posted on Dec 2010]
Need:The other day I thought about this idea of having a community wi-fi network. I am sure it has happened to you as you are traveling or driving somewhere your iPhone (or other device) will ask you if you want to join a random wi-fi. These random wi-fi networks will change as you continue traveling because you start losing some connections and gaining others.
Now, imagine if all these random connection were tied to each other. So you iPhone would jump from one network to the other like cellphone towers. The only thing that you would need is to (1) be able to standardized all network security and connection settings (2) avoid the free-rider.
Description:The way I thought we could do this is by creating a community wi-fi. You would need to register your own Wi-Fi network to be able to access this community network. This would avoid the free-rider problem. The key problem that I haven't been able to resolve is how to avoid security problems.
Potential:It can probably be a subscription model but I'm not sure how much people will pay for the service. It would be more probably something that is free or freemium.
Update [10/2011]: I just heard that there is several of these type of networks around the US. Not sure if they work exactly like I described but they are call similarly "community network".