Flutterby™! : WiFi in coffee shops

As I alluded to when I linked to that Chronicle article about WiFi, I was chatting with Brian over at San Anselmo Coffee Roasters a few days back about putting 802.11b in the shop, and he complained that it would be many hundreds of dollars a month. Paul Victor Novarese has been watching TV and seems to have found a disconnect between SBC's TOS and their ads. I've been through the SBC site and I think, if I'm interpreting it right, that he could use any of the small business plans (starting at circa $80/month) as long as he didn't charge for the service. Unfortunately I initially thought he could keep access to customers by just turning off the router when the business is closed, but when I think about it more I can't see a good way to do this without a fairly smart router that can do things like make sure people aren't spamming from that IP. Anyone got suggestions?