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I made a mandelbulb program (from scratch) in C#, but my current coloring algorithm is... underwhelming. A quick render I did is over here- http://khyperia.deviantart.com/art/The-tunnel-to-everywhere-288260051 (basic information about the program is also on that page)

My question is this- What is a good coloration method for a 3d fractal? Currently I'm doing "orbit trapping", where I take the smallest absolute value and use that for color. This, however, produces the rather dull, everything-the-same-color look in that image I linked. I also cannot use total iterations until escape, as the final point I use is at an unknown (yet very small) distance away from the fractal, so the result would be quite random. What other coloring methods are there, and how do I implement them?
(google has failed me on this, not many people have done the mandelbulb so documentation is sparse)

Hello, Mrz00m put a link on my own Mandelbulb coloring question to here. I figured I might as well share that incase any of my questions are similar enough to yours. The topic is here: http://www.fractalforums.com/programming/basic-3d-fractal-coloring/

I had tried distance estimation but don't know how to calculate a derivative so I had to simplify the equation (which makes for a lousy distance estimation). The distance estimation equation can be found here: http://www.subblue.com/blog/2009/12/13/mandelbulb