Update 2010-06-12:
change number of cycles in the color table with 'j' and 'k'
- small speedup, updated libs
Update 2010-06-09:
- save and load status and parameters to disk with F9-F12

Core features:
-BuddhaBrotMT is multithreaded and should be quite fast ;)
-Basic Buddhabrot (type 0), Anti-Buddhabrot (type 1), special mapping of the Buddhabrot (type 2)
-Basic Buddhabrot sped up with Metropolis–Hastings (type 3): http://en.wikipedia.org/wiki/Metropolis_hastings
-Switching between single layer and 3 layer color mode
-2 different zooming modes, one for the window and one to make the render size bigger
-Writing out render to 8-bit or 16-bit PNG, largest one I tried was 45915 by 28602 ;)
-On the fly changing of many parameters
-Smooth color cycling to get all psychedelic

You can download 32 bit and 64 bit versions for Windows and Linux in the Download section.
The renderer itself doesn't include any help so check out the Help section if you want to know how to interact with it.

Below you can see an example of a Basic Buddhabrot in color, you can find more renders on the different image pages.