I just got an Apple TV and Airport Extreme and was surprised how much heat the Apple TV puts off. I was hoping to save rack real estate and stack them but don't want to fry the extreme. I have googled and can't really seem to find anything about stacking them. They look like they are meant to be stacked, wondered what everyone else is doing. for the record, I will be stacking the apple TV on top, as it is quite a bit hotter.