The WSJ reports on a service in the Czech Republic that lets users sell their Wi-Fi connections to their neighbors (link good for seven days): This offering isn't as good as a similar one from WideNet and Wia in the Czech Republic which will do the billing for customers.
The WSJ article covers a company called CzFree.net which requires customers to buy over $800 worth of gear and then allows them to sell connections to their neighbors. There is no mention of CzFree.net handling the billing, which I think is pretty key. I wouldn't want to have to deal with trying to make my neighbors pay me for something. Also, it doesn't appear that CzFree.net has a deal with a landline broadband provider, like WideNet does, which makes the legality of reselling connections questionable.