chalkbot
http://www.google.com/search?q=chalkbot&hl=en&safe=off&biw=1632&bih=957&prmd=imvnsl&tbm=isch&tbo=u&source=univ&sa=X&ei=3JisTv2AGaKOigKntrSCCw&sqi=2&ved=0CE4QsAQ