Mirrors turning to look at you
The mirrors in rAndom International and Chris O'Shea's Audience project chat amonst themselves until something catches their collective eye.
When members of the audience occupy the space, the mirrors inquisitively follow someone that they find interesting. Having chosen their subject, they all synchronise and turn their heads towards them. Suddenly that person can see their reflection in all of the mirrors. They will watch this person until they become disinterested, then either seek out another subject or return to their private chatter. The collective behaviour of the objects is beyond the control of the viewer, as it is left entirely to their discretion to let go of their subject.
This Vimeo video is a good look at how the project works. (via sippey)
Update: New from O'Shea is Hand From Above.
Unsuspecting pedestrians will be tickled, stretched, flicked or removed entirely in real-time by a giant deity [on a large screen].