I've been playing with Incendia (1.5 R2) lately and it's really great...
I mean, I've been interested in fractals for a decade, but this software is one of the most accessible AND most powerful fractak generator I've ever seen.
(Or I'm smarter now than some years ago :p)
But for those who want to try it, really, have a look at the wiki and its tutorials. Only 10 minutes are required for the basic tutorials (*really* 10 minutes) and they explain a lots of things I wouldn't have guessed alone.