VW Bug offers on a new “canvas” for marketing

In-Brief Videos is all for using Expo markers to make a point.  But, VW took that concept into power drive by putting markers in the hands of children (and the public) and letting them express themselves on a new VW bug at a recent DC area event at the Kennedy Center. There wasn’t much room to write when we got there but it got me thinking, what other (simple) medium could we use to make a point? Any ideas?