I don't know if it counts since this is techincally a posed picture, but this is Tails at 8 weeks sleeping wrapped in a towel because he was shivering after a bath.
Here's another favorite: This is like Escher's Drawing Hands (http://dalesdesigns.net/escher/drawing_hands.jpg if you don't know what I'm talking about, one of my favorite pictures ever), except with cats using each other as pillows.
As a single cat owner, I don't have any cat pile pictures. And Holland is barely bigger now than when I adopted her as an older kitten, but here are a couple of my favorites... at least they make me say aww...