I must say I'm intrigued by the reaction to my "wireless for the people" experiment.
I am not charging people for using my spare bandwidth. So there is no profit to be made.
It's all masked behind NAT so as far as my ISP is concerned there's a single connection.
My personal PC's are secured on their own subnet and are all hardwired, so there's limited risk of them being compromised.
To illustrate it, I've got an old PC with 3 NICs in it running monowall. (live cd firewall) Labelled as such, WAN, LAN and LAN2.
WAN is just that.
LAN is my person space: 172.16.10.0/24
LAN2 is my wireless router running simply as an access point: 192.168.0.0/24
Access to 192.168.0.1 (the router) is blocked at port 80, so the router configuration is inaccessible from the "open" network.
Access is also blocked from LAN2 => LAN so my personal network is secured at that.
I've also set up traffic shaping (QoS) to give higher priority to my own traffic in addition to giving P2P traffic the absolute lowest priority.
Additionally I am logging all DHCP leases on both sides so I have the MAC address (and initial connection time) of anyone accessing anything through my network. If I put forth just a little more effort I could set up a proxy so I know what people are accessing as well.