I have been a great fan of nicely designed case backs for a while now. There are some awesome case backs on watches nowadays, sometimes I like the back of a watch better than the front. So, post your favourite case backs here, the more the merrier. Even if they are so ugly they should be hidden!
Here are some on my watches. Allthough the Blackwater has no significant engraving, I still like the tool like look of the back.