Lopex writes "Gizmodo has a story about Hektor, a graffiti robot. Apparently it is for the extremely geeky (or perhaps extremely lazy) tagger. Hektor.ch has photos, information (pdf), and a movie (15 Mb) of it in action."
I've never been canoeing before, but I imagine there must be just a few
simple heuristics you have to remember...
Yes, don't fall out, and don't hit rocks.