Adding two more rendering apps, and they're both currently free (!!!) and work nice on my G5. In case they disappear, I'll keep the zips, and they already have the serials with them, so all is good.
And you can laugh because Bryce currently works on Intel, but hasn't been updated for neither Lion or Mountain Lion and it looks like it won't for at least another year.

And that's probably my favorite program, so it sucks because I'd have to boot camp my Intel Mac to even use it on it.
The setup files might freeze/look like it force closed on you for some reason (all their software is buggy though), but if you leave it for 5 minutes, it'll be okay.
Oh, and OS X 10.2 support in Hexagon...
Hexagon 2.5
Requirements: Power PC G4 Processor® (G5 or greater recommended), 1 GHz (1.8 GHz or faster recommended), OpenGL compatible graphics card with at least 128 MB RAM (256 MB+ recommended), OS X 10.2 or above, 512 MB RAM (1 GB+ recommended)
Hexagon 2.5 is a modeling application that allows artists to create their own 3D objects from scratch using a freehand brush-style set of tools. These freehand brush modeling tools let artists sculpt 3D models by pulling, pushing, pinching, inflating and smoothing the geometry. The speed at which you can create a complete model is astounding. With support for graphics tablets, users can design their own creations with precision and flexibility. Through the new 3D paint and UV-mapping tools, users can quickly apply textures using brushes, imported textures or choose from a large choice of predefined textures.
http://cdn-sw.daz3d.com/hexagon/Hexagon_2.5.1.79_Mac32_bundle.zip
Bryce 7 Pro
Requirements: 700 MHz (1 GHz or faster recommended), OpenGL compatible graphics card with at least 128 MB RAM (Drivers supporting OpenGL 1.1 recommended), OS X 10.4 or above (Not currently compatible with OS X 10.7 Lion), 512 MB RAM (1GB recommended)
For more than a decade, artists of all mediums have known Bryce as the affordable 3D software for achieving breathtaking realistic imagery. Bryce 7 gives you ability to work faster and create more realistic environments than ever before.
http://cdn-sw.daz3d.com/bryce/Bryce_7.1.0.109_Mac32_bundle.zip