Because it seems to be getting some good press here lately, I'll toss in the link for Google SketchUp
, a free 3D design program with a very intuitive interface and some impressive capabilities. The free version doesn't allow exports to other 3D formats, so you're pretty much stuck with the rendering tools it has, which are more along the lines of architectural rendering - which can be very useful for the right applications, such as creating comics and the like; there is also a Pro version that has more tools and abilities, and can export a number of 3D formats, so you can then modify, polish and render them in more traditional applications.
**** Highly recommended
Also, a program called Hexagon 2.0 is available now from DAZ, the creators of a great deal of high-quality content for Poser, and also of their own Poser-type program called DAZ|Studio (also avaialable for free). Hexagon is a full-featured 3D program, which includes tools for UV mapping and 3D texture painting. DAZ just bought the company that created Hexagon, Eovia, and as their introduction to the software, DAZ Premiere Club members can buy the full program for $1.99
for a limited time (it's normally priced at $269!). Membership is only $7.95, though, and you're not committed to any term, so you could get the program for, at most, $9.94, a bargain in anybody's book