Here you will find a list of links to products or pages that I find useful.
Daz3d – Makers of Daz Studio, a “POWERFUL and FREE 3D creation software tool.” They also have a large marketplace of quality 3D content and monthly freebies.
Renderosity – A digital art community with a large marketplace of 3D content, but also a nice collection of user created freebies.
Hivewire – “A destination where everyone—new or experienced—can come to share, shop, and sell digital content.” Their Horse and Dog models are excellent.
Blender – “Open Source 3D creation. Free to use for any purpose, forever.”
Blendswap – Free user/community provided .blends and other resources. A great place to learn by examining other peoples work.
HDRI Haven – Hands down the best place on the web for quality FREE CC0 HDRI images that can be used as the sole source for lighting in Daz Studio. I highly recommend them.
CG Bookcase – A great place for high resolution CC0 tile-able PBR image textures. While these are more likely to be used in modeling, they can be used in Daz Studio to change the look and materials of existing models.
CC0 Textures – Another great site with loads of high-rez CC0 PBR textures. They add a new texture almost daily.