Ok, this group seems fairly tolerant of whacky ideas that may never actually be built, so I will kick one in: a bot that climbs windows with suction cups.
The original idea comes from those toys that will roll down a window on suction cups. But how hard would it be to make one climb? Maybe something similar to the suction cup on the bottom of a pencil sharpener can be used with a little worm drive to actuate or de-actuate the suction cup. For steering each of the two cups has a motor to rotate the rest of the body relative to the fixed base in the same plane as the window. Then a third motor swings the non-fixed suction cup into position so it can be attached to the window and the other cup detached. Feedback from motor torque can insure that the forward cup is actually fixed before the back cup is released. A couple of contact switches around the outside, or on the back side, of the suction cup can make sure there is a surface to attach to. I can see it now . . .
Solar powered window climbing bots clean skyscraper windows and rescue stranded birds.
- James B