Caligari's home page
Free download for trueSpace 3.2. It's a 22 MB file, so fair warning to those on dialup.
30-day trial download for trueSpace 7.5 (cost is $595 but that's not bad when compared to 3dsMax and Maya!) From the site, a brief description of trueSpace:
trueSpace7.5 is a powerful tool for 3D presentation, design, animation, games and art. It is also well suited for content creation for distance learning and emerging 3D social networks.
I've never used this app myself - I use Bryce - but I've seen plenty of images created with it, and they're very effective.
[Mods: sorry if I posted this in the wrong forum. Had a hard time deciding between here and the graphics forum.]