Have a look at this guys 3D art work he does on the sidewalk you really have to stare at it as it looks so real.
The Incredible Art Of Julian Beever!
http://www.google.ca/search?q=julia...niv&sa=X&ei=uc-0TsrHGqKNigKY-9w7&ved=0CCEQsAQ
The Incredible Art Of Julian Beever!
http://www.google.ca/search?q=julia...niv&sa=X&ei=uc-0TsrHGqKNigKY-9w7&ved=0CCEQsAQ