Ascending and Descending
The image below was created for Photoshop contest, which was took part at the Woot! site. The main task was to create an image, which contains the name of the site as easter egg. Here, we see words "woot" on roofs of the monastery from Escher's artwork "Ascending and Descending".
The image was found at http://www.woot.com/Forums/ShowPost.aspx?PageIndex=16&PostID=273935