Tilt Brush, according to its developers, “is a Virtual Reality Tool that paints the Space all around you. Paint thick, three-dimensional brush strokes, smoke, stars. Even light.” Check it out:
I always dreamed of giving Photoshop this kind of expressive painting power; hence my long & ultimately fruitless endeavor to incorporate Flash or HTML/WebGL as a layer type. Ah well. It all reminds me of this great old-ish commercial: