We're having our kitchen redone and I would like to integrate our free-standing stove into the island unit.
Where would be decent place to put the stove master switch within this island as there are no walls available directly nearby?
You'll want to place the switch in a convenient accessible location, where it will be out of the way but still usable. Without some type of plans/drawings/pictures of the island, the answer will have to be fairly generic.
I'm going to go the other way from Tester101 and suggest you DO put it inside one of the cabinets in the island. That's what we've done in our house in New Zealand.