I recently found a very interesting program named the Chaoscope which can render out very interesting images however controlling the output and shapes does need some figuring out. The output are very amazing shapes and effect which could be usefull for working as a background for other designs. There are possibilities to make smoke like render which often are hard to photograph pictures. And also you can use it to make a close like design like the old Adobe packaging designs. However you need a decent computer to render high quality renders.
If you are interested in this program and want to render these kinds or pictures got Chaoscope.org for more information and to download the program. If you want to see more of these kind of rendering of mine visit my Chaos set on Flickr.