Yeah i've smoked from an apple before, it was ok, but I have a better food pipe..

A carrot!! Just make it like you would an apple or potato, but just use a carrot! Also (since I ussually only use a carrot while i'm at work, since I work in a restaurant), I'd suggest baking the fruit/vegetable for about 2 minutes before smoking out of it. This way it dries up all those fluids and won't be so nasty if you're toking up with other guys.