Distorted Menger Sponge
Kaleidoscopic IFS fractal
I figured out why Pixel Blender kept crashing: it was because of a GPU timeout imposed by Windows Vista. Turns out GPU kernels are only allowed to run for two seconds. But it is possible to change via the TDR Registry Keys.
These keys were not defined in my registry, but I added a DWORD TdrDelay = 30 and a DWORD TdrDdiDelay = 30 key to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\GraphicsDrivers which sets a 30 second window for GPU calculations. You have to restart Windows to apply these settings. Be advised that changing these settings may render your system completely unresponsive if the GPU crashes.
The picture above is a Menger with two rotation steps, and an extra folding step.