For Volumising Mandelbrot's Equation the Mandelbulb is worth a look:
"In 2006 Daniel White inspired by an idea of Rudy Rucker developed a mathematical equation with the potential for a real 3D equivalent to the famous 2D mandelbrot set. With a modification by Paul Nylander in 2009 the Mandelbulb was born on fractalforums.com"[1][2]
[1] http://www.fractalforums.com/still-frame/the-discovery-of-th...
[2] http://www.skytopia.com/project/fractal/mandelbulb.html