How have advertisers missed the opportunity to turn subway grates into pixelated, LCD-style ads?
With a $10 bag of foam packing peanuts, like the ones stuck in the grate above, you could saturate Times Square with your message.
I haven't demonstrated this idea in the wild for fear of triggering a rush that would turn grates into billboards and interfere with the crucial exchange of street vehicle exhaust and subway tunnel air.