there is the Mathworld page. For a whole lot of explorations

Playing around with complex numbers A conformal transformation is a kind of function
defined over all complex numbers that has the basic property of being differentiable, i.e.
continuous and smoothly varying. Such a function defines a transformation on the plane that
has the property of conserving the angles. This implies that on a very small scale shape is
preserved in such a transformation. Almost all these images are done with a Gimp plug-in
called Mathmap. Then it is just a matter of finding an interesting transformation. For a