Tomas Pettersson has created a pretty amazing sculpting tool in his spare time: Sculptris. The Windows-based software provides a very intuitive way to model freeform sculptures. Using simple controls, a designer can quickly produce symmetrical shapes of great detail and beauty. You must watch the video to appreciate how easily an artist can produce amazing models.
Right now Sculptris is free, although creator Tomas would appreciate a donation if possible:
I don't want to demand any payment for the application, but of course I will appreciate a donation if you feel like it is valuable to you. Take a moment to consider what it would be worth in your particular case.A pizza? A movie ticket? A day's salary?