This is a great idea! William and I talked about doing similar, back when we first resurrected the Pub - along with incorporating a Google Map or something.
The Forum Message Board system we use, offers a bunch of third party plugins/utility add-ons. It's just a matter of pawing/digging through the library/database and finding something that suits our needs.
It's also might be something we could employ someone to make for us, depending on the scope and cost.