Tired of Cubes and Spheres?
Recently I've had the urge to play around with 3D development and I wanted something a little more descriptive than just a bunch of cubes and spheres floating around in my prototypes. I know Blender is free, but I'm a programmer first and foremost and I don't want to spend the time learning such an elaborate piece of software just to scratch the itch of a little better programmer art.
That lead me to find Wings3D (link below). It's a very simple open source polygon editor that only takes a couple of minutes to learn how to use. You can really go crazy with the things you make in this program. From simple low-poly models (a personal favorite of mine), all the way up to high-poly models you could use in a professional release (you could use low-poly models for release also, but I was just illustrating the range this software encompasses). In just 20 minutes I created my first table thanks to VscorpianC's tutorial over on YouTube (link below). After an hour I had created my first asset I plan on using in a project I'm prototyping at the moment.
I do want to mention that even though I'm suggesting this off of the basis that I'm using it for better programmer art, it is a very capable piece of software and the depth of what you learn and create is entirely up to how much time you are willing to spend learning the software. So if you've been looking for a free, open source modeling program to use for making your next commercial project I don't see why you couldn't use Wings3D for that as well. Although it is worth mentioning that this doesn't cover animation, so you'll need another solution for that problem (animating in Blender, Unity3D, or any other program capable of animation are some options).
http://www.wings3d.com/
http://www.youtube.com/playlist?list=PLP3-5QSIC-VcsndQX3HR1hGDFwDbpcOXh
Good luck and have fun!