The Originals Factory is an art bot by Liat Segal & Assaf Talmudi:

The Originals Factory is a work in progress fusing together and questioning digital, mechanic and plastic approaches to art, abstraction and originality. It is basically a DIY robot, built and programmed to create landscape paintings in the style of American abstract expressionism.
The computer system uses real time video input to control motor movement and pump actions to release paint drops on a large canvas. The drops are then drawn downwards courtesy of gravity, leaving thin colorful line marks.

I like how, unlike many art bots, the robot only has a marginal control over the medium — it can control the amount of paint, and what color, and where, but gravity controls the rest.