From the home page:

XaoS is a fast portable real-time interactive fractal zoomer. It
displays the Mandelbrot set (among other escape time fractals) and
allows you zoom smoothly into the fractal. Various coloring modes
are provided for both the points inside and outside the selected
set. In addition, switching between Julia and Mandelbrot fractal
types and on-the-fly plane switching is provided.

Homepage:
http://matek.hu/xaos/
