But you may be picturing something different that what they are. They aren't sis kebabs (or kebap, as I think they actually spell it) - more a big spit with stacked, seasoned meat that they would shave meat off of to put in the pita or roll with sauce. Here's a picture of a doner kebap meat cooker:
Not the best image, but I couldn't find many. The outside gets kinda crispy and it all has spices all through it and then you can get various things on it - usually a yogurt and garlic sauce and peppers and such. OH, it's good. We'll have to find a Turkish restaurant someday that serves 'em. ;-)