Just getting into 3D imagery? Have you tried these programs yet?

I'm by no means a master of 3D - yet - but I have tried a few programs and can recommend some great ways to get started. Like...

How about Bryce? PC version, of course, but Mac is supported too (just search for a link). Be careful to read the whole page or you'll miss the free rego code....
 
Bryce (Personal Learning Edition) - Free software downloads and software reviews - CNET Download.com

This Personal Learning Edition (PLE) of Bryce 7 is a full-version with no watermarks or limitations of any kind in the program itself. The licensing allows for strictly personal, non-commercial use. SERIAL CODE: BDZPLED-070-0000000-NBA-001-HBUVMLF

Bryce is an award winning, fun, feature-packed 3D modeling and
animation package designed to allow new users to quickly create and
render stunning 3D environments. Bryce combines exceptional power with
an innovative interface for incredible ease of use. Add wildlife,
people, props and more to your scenes via the DAZ Studio character
plug-in in addition to terrain, water, sky, rocks, clouds, fog,
vegetation, and architecture for which Bryce has long been the standard.

And its companion, DAZ 3D Studio...

DAZ 3D - Free 3D Software and 3D Model Providers

DAZ Studio 3 Products and Bundles
DAZ Studio is a free, feature rich 3D figure design and 3D animation
tool that enables anyone to create stunning digital imagery. This is the
perfect tool to design unique digital art and animation using virtual
people, animals, props, vehicles, accessories, environments and more.
Simply select your subject and/or setting, arrange accessories, setup
lighting, and begin creating beautiful artwork.

And Blender, an enormously useful tool for 3D work... you'll see Blender-ised 3D images built into applications all over the web...

blender.org - Home

Blender is the free open source 3D content creation suite, available for all major operating systems under the GNU General Public License.

And of course iClone 4 from Reallusion... easier to use but still powerful with a free version to boot... the real-time filmmaking is a standout.

iClone - Solution for Real-time 3D Animation 3D Stereo Video

Real-time animation evolves with 3D Video FX, motion paths, HDR and rapid drag & drop creation inside iClone4. iClone4 combines real-time filmmaking & video production inside one powerful engine. The result is a streamlined production tool for motion graphics, 3D animation, video compositing and 3D stereo creation.

That's all for now - it'll get you started anyway.