NeverWet is a water-repellent spray that can basically keep anything dry. It's cool, if not the most practical thing in the world. But apply it to a footpath, let it rain, and magical things start to happen.
The project is the work of Seattle-based artist Peregrine Church, whose (entirely laudable) mission was to "make people's rainy a little bit better". To do that, he sprayed NeverWet through a stencil onto the footpath, making select parts of the footpath completely waterproof.
The result, as you can see above, is games and illustrations that appear when it starts raining: : the dry bits of footpath carrying the message stands out from the wet. You've got everything from hopscotch to inspirational messages -- basically, anything you can stencil onto a footpath.
The art installations are in Seattle (which makes sense, given the climate), but anyone armed with a $30 bottle of spray and some cardboard can go make their own. Just add water. [YouTube via Colossal]