It’s a real shame that selfish commercial interests have made it so difficult for communities to set up their own shared WiFi networks on a large scale, but that’s the way it is for now. Apart from services like FON the reality is that the most pervasive public networks all cost money. However there is another option if you’re willing to take a bit of time to install a freeware solution.
Connectify Lite is a freeware program which converts your humble laptop into a full blown WiFi hotspot. What you’re basically doing is sharing your computer’s connection with anyone else you like, but you do get a decent amount of control to prevent undesirables logging on and ruining the fun. The freeware version also offers limited sharing of 3G/4G Internet connections, as well as cut down file sharing. For full functionality you need to buy the Pro version.
One cool use of this software is to share your laptop connection with your smartphone, a kind of reverse tethering, but I’m sure there’s other uses that it can be put to. I’m looking at you, indie coffee shop and bookshop owners.