Well, then maybe you should stop offering free Wi-Fi access to the world, eh? If your SSID is being broadcast, and anyone can connect, then it’s not their fault they didn’t know you had a bandwidth limit. Stop broadcasting the SSID, turn on WEP, or use MAC screening.
I’m WPA secured, thanks. That doesn’t change the fact the fact that unauthorized use of my connection would be theft, not trespass.