This fellow, Edgar Mueller, is amazing. His chalk street art is fantastic, and there are quite a few others like him as well. I can't stand graffiti, and mostly because it's usually applied with malicious intent and done to leave a permanent and damaging mark on personal property. There are legitimate artists as well and this however is council-sanctioned, and quite an eye-full for any passers-by. Brilliant!
Info:
http://www.metanamorph.com/
videos:
"The Crevasse" -
http://www.youtube.com/watch?v=3SNYtd0Ayt0
"Street Painting 3D" -
http://www.youtube.com/watch?v=6I81KAxFHAk