Fractalicious is an app which calculates vectorbased fractals (that means, no Mandelbrot etc., but ferns, trees, Sierpinski triangles, etc.). It's very easy to use - use two fingers ("pinch") for zooming, moving and even rotating the fractal (note the "and"!), or drag a control point to change proportions/angles. http://code.google.com/p/fractalicious/