There's a movement afoot to provide open connections - many routers and access points provide for a public channel available that is bandwidth limited to 1Mbps; basically a crowdsourced public hotspot network outside your own home network. Doesn't solve the who pays for it problem, has some security implications, but does allow for that random "gosh, I need to be connected right now" connundrum we've all faced.
But to address your question - yes - I have thought about it; but all my neighbors also want every available feature and channel that even they don't use, and want to share the entire bill rather than just the IP portion. I don't use cable except for the IP address - and dislike the idea if I even get basic-basic cable I subsidize the guy that has NFL on 24/7. My strong preference is for providers to move to a basic menu approach: I want DVR service, local HD content, and a single premium channel with on-demand (GoT addict so I have to buy the DVD when its available). I don't want 'free sports,' HSN, TNN, ComedyCentral, or any of the other fluff they offer in their 200+ lineup.
So Phil, any time you want to move next to me - I'd be happy to share my wireless with you; currently a couple yagi antennas and you can get almost a Gb over the air with consumer gear. And 50 feet of CAT5e is cheap, just in case the wireless band is full.