Street corner pedestrian proximity detectors.

Pelican Crossings emit noises to assists negotiating busy roads. Why not employ this success story for busy street corners. Attach proximity sensors onto 'Black Spot' street corners that activate when you approach, and as you walk near emit a note, that descends as you draw near the apex of the corner. As you pass the apex, the note would begin to raise again until you are out of range (say 10 feet). Like a very big Theremin. Thus if you are in a hurry, you can confidently negotiate street corners at speed without fear of walking slap bang into somebody doing the self same thing coming the other way.

Plus, if you are feeling playful, maybe you could organise friends at cross roads to leap in and out of range at unison to recreate popular Motown hits. See what the RIAA make of it.

Sadly, the sensors would inevitably have to be automatically deactivated if there were many pedestrians wandering by, at which time they wouldnt be required anyway.