Turbosquid is a site with tons of assets for 3D and CGI. I like it because many of the models are free and it can be helpful to download some and see how the shapes are assembled if you are learning how to model in an application such as Maya, 3ds max, Cinema 4D, etc. Some of the models are also already rigged and so the same idea might apply to that and even texturing, now that I think about it.
I shared this with my online Maya class and I thought, hey, I should post it here, too.
Eric Chamberlain 