This is essentially what I do. I do have my housemates pay a share because they have access to a hardwire connection, but I have an open AP which my neighbors, guests, and anyone within line of sight down the street use. I have plenty of bandwidth that goes unused so I don't mind - I pay to have fast bursts of traffic, so I don't have a problem letting other people use what I don't. The only thing holding me back from having more people use it is locations nearby for repeaters. But I may put more effort into getting neighbors interested in hosting repeaters so that may change.