http://www.artifice.com/dw_lite.html
DesignWorkshop Lite is a simple to use 3D program.

http://www.povray.org/
PovRay is a free ray tracing program, just for the 3D fanatics.

http://www.animateclay.com/download.htm
Anasazi Stop Motion Animator is a free program for making claymation animation. There is a lot of information on how-to-do at the homepage.

http://www.fresherimage.com/3D_Animations/Bullets/index.html
You can get heaps of free animated 3D images for your web pages.

http://www.3dstate.com/
3D engines for web building and gaming worlds.

http://www.askoh.com
freeCAD is a 3D CAD program with moving simulation. It looks like a
very good way to learn the basics of this type of program.

http://www.3dtextureworld.com
Get free textures here to apply to your 3D creations.

http://www.amabilis.com/
3D Canvas is a free 3D modelling package. Tutorials available too.

http://www.aliaswavefront.com/en/products/maya/index.shtml
The free personal training version of Maya is now available here. If you want to wait for a month, it will be on the next Digit magazine cdrom. There are additional tutorials and free samples to download from here too.

http://www.anim8or.com/main/index.html
Anim8or is a 3D modeling and character animation program

http://www.softimage.com/products/exp/v3/
You can get to learn SoftImage using their free cds. This deal looks a bit like the Maya one, as a watermark is employed, but they have left the hair plugin in place. It's free, so go for it if you like. Check the system requirements first as I think it is only Windows platform.

http://www.insanesoftware.de/index.php?page=freetools/terrain.php
Terrain Texture Generator is a small toy for those who like to create interesting shapes from images.

http://web.tiscali.it/GiulianoCornacchiola/Eng/
Now3D is a 3D raytracing program.

http://www.sidefx.com/products/apprentice/index.html
Free Non-Commercial Version Of Award-Winning Houdini 3D Software Available

http://www.ndl.com/roi/ndl_dmna.html
2 free downloadable plugins for Maya and 3DS Max.

http://www.kurtz-fernhout.com/PlantStudio/index.htm
PlantStudio is freeware for creating plants, (non woody) of all types for your projects.

http://www.behemot.com/
Behemot Editor is a graphics program which allows to model and render 3D objects and scenes.

http://www.steffengerlach.de/freeware/
ZPaint is a program for making 3D objects easily. Looks like fun.

http://users.hol.gr/~sternas/index.htm
GaiaCAD is another project by the above programmer.

http://www.doga.co.jp/english/software/dogal1/index.html
DOGA-L1 is a 3D animation and CG creation tool.

http://www.artofillusion.org/
Art Of Illusion is a freeware Java based 3D modelling and rendering program.

http://www.caligari.com
http://www.caligari.com/products/truespace/ts3/resources/default.html
I think this is the page for getting the free version of Caligari's TrueSpace 3D program. There are tutorials here anyway. Rego is free. If you need to, use http://www.caligari.com/download/ts32.zip

http://members.fortunecity.com/vincentyu2003/
Windows based 3D CAD/Modeling package with fast solid modeling op and simple 3D viewing.

http://www.blender3d.org/
Blender, the open source software for 3D modeling, animation, rendering, post-production, interactive creation and playback. Available for Windows, Linux, Irix, Sun Solaris, FreeBSD or Mac OS X.