You can use your computer to create beautiful free form fractal flames. These fractal flames and their associated editors and rederers have been around since 1992, and they just keep getting better.
You can now run the software standalone, creating these images for your own enjoyment, or you can participate in a larger community of people creating these images via a screen saver which generates the images and allows you to vote and thus influence the longevity of images being created on the computers of others.
Create your own: [Apophysis]
Get the "Electric Sheep" screen saver: http://electricsheep.org/