I built an automated fractal renderer (took a month or so), so I can leave it rendering and after a while 10-20% of its output will be worthy of saving [and perhaps 5% worthy of uploading here]. Here and there I improve it. Most of the code is in lua, using c++ game engine.
Next planned features:
low-res previews to allow some control over what to render.
some degree of customization/user input
more options for stylizing / image warping
Eventually I'll hire someone to get high-precision numbers working, so I can zoom as far as I need, but there's enough detail using double precision for