A device could be made to work that way. I'm not aware of any that have that feature built in. You could certainly use something like Llama to turn wifi on or o

A device could be made to work that way. I'm not aware of any that have that feature built in. You could certainly use something like Llama to turn wifi on or off depending on where you are located, but that isn't quite what you asked for. I don't know if Android or iOS have APIs available for an app to automatically add/remove wifi networks, but if they do, then that would be useful for achieving what you suggest.