|SkyArt by Thomas Lamadieu|
Today: look up between buildings at a little patch of sky. Use the shape of the sky to create an image. This is the work of French artist Thomas Lamadieu who was inspired by the overhead skyscapes of his home town of Avignon to populate those spaces with whimsical characters.
There are loads more examples on the SkyArt page of his website.
And there are some cute examples of another kind of undoctored 'sky art' on WebEcoist.