This is the new room key being used at Caesars Palace. I think it's only at the Diamond and Platinum check-in desks, but not really sure.

Another lenticular design, like the evel knievel key done a couple of years ago. Tilt it slightly and you see another image. Here's one scan showing both the 1966 and 2006 views of the hotel and fountains.

I have a couple of traders for slot cards I don't have from outside Nevada.