I'm a big fan of robots that are purpose-built to do something wonderful and useless, especially when that thing is against the law. Designed by So Kanno and Takahiro Yamaguchi, the "Senseless Drawing Robot" (that's them calling it senseless, not me) combines random programming with even more random motion to spray paint randomness2 along whatever wall you park it next to. One thing's for sure: humans aren't allowed to be doing this.
For such a random mechanism, those patterns appear to have quite a bit of artistry attached to them, but I'm probably just projecting or something. While I'd be happy to unleash this little guy around the house (or the IEEE Spectrum offices, for that matter), for the moment, you'll have to travel to Tokyo (and back in time about a month) to see it in action at Utopinism.