Sculptris is marvelous, comes from a guy in Sweden named Tomas Pettersson, aka DrPetter,  www.drpetter.se - he is a game developer and has created a bunch of tools for his own use and makes them available for free, this one (Sculptris) is my favorite but if you're also looking for ways t make audio snippets, sound FX and music, there's more, plus he's also posted a bunch of his games. See my drpetter-fan page at www.thebest3d.com/gamedev  (oh and if you're into gamedev, while you're there, check the link to the latest version of the 3drad game enbgine, free also, just updated.
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You can import/export to Wavefront .OBJ format. Seems to work in my tests so far, with other apps. I'm sure it'll work with Bryce too, and should quickly become the poor man's alternative to Zbrush, in my prediction.

Sculptris also has a bunch of similarities with Curvy 3D, www.thebest3d.com/curvy, but then again there are also some significant differences. They're al tools in their own rights, but boy what a great toy and tool this one is. If you haven't tried Sculptris, you're missing out on something remarkable. If you have a Mac only, see about getting some VM such as CrossOver, VmWare Fusion or Parallels desktop for Mac and please tell us if it'll run inside of those VMs.

Version 1.0 of Sculptris was just released a few days ago, the project started less than a year ago - remarkable! totally amazing!

in short: two thumbs up, and I wish I had more hands, more thumbs