Attached Link: http://www1.sphere.ne.jp/mizno/main_e.html

And, if you're on a PC and want to really play with metaballs, Metasequoi lets you use any of the primitives as a metaball object. You can boolean there too, convert to mesh, and export to Bryce. The freeware version is the one that exports. Unfortunately that program is undocumented and it takes a bit to figure out. I have some tuts up and plan on doing more at www.annsartgallery.com/eric.htm