Don't worry about needing artistic sensibilities to produce street art -- if researchers have their way, all you'd need is a good photo and the right tools. They've developed a robotic spray can that produce large murals based on pre-supplied images. By tracking the can using a PC, two webcams and QR codes, the system automatically knows when to spray to replicate the intended picture. All you have to do is wave the can over your target area and let the hardware do the rest -- if you're producing a multi-color image, you just swap cans.
This technique would most be useful for creating building-sized artwork, but there's potential for more. If it's adapted to work on non-flat surfaces, you could spray paint globes and any other object that could stand some sprucing up. Although it won't have the same impact as a completely from-scratch painting, it might well bring art to places (and people) where it simply wasn't an option.