Stunning display of just how far CSS can be taken, given sufficient patience and a little imagination: There are no images on this page. Near as I can tell, he ran a bitmap through an image analyzer to determine the value of each pixel and translated each one into a corresponding DIV with matching CSS color value. He then created PHP transforms to let you drop channels, go grayscale, etc.
I’m not sure exactly how useful this is in practical terms, since the amount of CSS it takes to create a photographic representation exceeds the number of bytes it would take to represent the image as a JPEG, but it does seem to open a lot of doors for as-yet unimagined CSS designs. You’ve got to respect him just for showing that it’s possible. Check the fawning comments.
Described this to a non-geek friend and his only reaction was “That guy must have a lot of time on his hands.” Some people, ah swear.