JHarris,
I have a couple of bike racks on my roof, but it's a bit of a paint to get them mounted.  Since our cross bars are so wide I hade to get an adapter to mount a secondary smaller bar above the factory cross bar that the bike racks then mount to.  It puts them up a little high, but since the racks are connected to the secondary bars all I have to do is unbolt the adapters from the factory cross bars and everything comes off together in one piece.  Here's a picture of the set-up at Moab last year.  I can take some closer pictures for you if you would like.
 
				
			 
			
		 
			
				
			
			
				"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong, it usually turns out to be impossible to get at or repair."
-Douglas Adams, Mostly Harmless