Windows/Mac/Linux: Usually, the goal of art programs is to accurately apply your vision to the graphics on your screen. Free app Alchemy takes a different approach, creating unexpected, sometimes haphazard shapes with offbeat methods to inspire art.
There are a number of different types of "brushes" in Alchemy, each that creates a different type of shape for which, in many cases, it is hard to predict the outcome. It contains a number of additional modules too, that allow you to draw without seeing the screen, randomise the shapes that appear, and even draw using your voice and an external microphone.
There is no undo button, cutting and pasting, or any of the other precision tools you usually get in paint programs — the idea is to provide an initial sketching platform that can inspire larger works of art. The above video, for example, demonstrates Alchemy being used in the initial sketching of a 3D model made with the popular ZBrush program (the first minute or so being the work in Alchemy). Hit the link to check it out for yourself.
Alchemy is a free download for Windows, Mac and Linux platforms.