I've been taking a small bit of a break from XNA code to delve into some of the free content creation tools out there. so far, Wings3D seems to stand out as a really good Free 3D art package. I'm able to easily create objects, texture them (using Paint.NET), export them to .fbx, import using the built in .fbx model importer in XNA Game Studio Express, and render them.
It's pretty satisfying to, with your own two hands (figuratively speaking), run through the entire content creation and consumption process. I'll refrain from posting up any of my hideous programmer art for now ... suffice to say that I'm still learning :-P
The next step will be to explore different approaches I can take for animation. In the meantime, these tutorials were a pretty good intro to working with Wings3D.