Hi all,
I thought I'd add a pointer here to a program I've developed called Gnofract 4D'.
-
http://gnofract4d.sourceforge.net/ - works on Linux (but not Windows)
- open source
- understands most fractint and ultrafractal formulas and coloring methods
- relatively easy to use
- has been around for 6 years with about 30,000 downloads
If you use Linux, give it a whirl!