Light Beam Animals
For those dreary cloudy days.
Based on the same concept as light-transmitting concrete, this would be a public service provided by cities in areas where there are way too many cloudy days (Seattle comes to mind). A dirigible would rise above the clouds until it was sunny side up and then drop a frame back down through them. The frame would be held in place by the same kind of optic fiber used in the concrete to deliver sunlight through the clouds to the seasonally-saddened people below. When they looked up they'd see various sunbeam animals floating beneath the clouds, slightly brightening their mood (of course, eventually some greedy ad agency will try to sponsor the entertainment, flashing "This cloud brought to you by ___" every so often).