Scott Kim has a wonderful talent at designing "ambigrams". Check out his classic book "Inversions" and his gallery of more recent work!

http://www.scottkim.com.previewc40.carrierzone.com/inversion...

An inversion is a word or name written so it reads in more than one way. For instance, the word Inversions above is my name upside down. Douglas Hofstadter coined ambigram as the generic word for inversions. I drew my first inversion in 1975 in an art class, wrote a book called Inversions in 1981, and am now doing animated inversions.