A very large community website with all sorts of resources for 3D: software links, objects links, textures resources and so on. Hundreds of websites to explore.
The best resource I could find for planetary maps. This website has huge maps (some are 4000 pixels wide) of most of the objects in the solar system, including satellites I did not know of. The most detailed ones are textures of the earth; some of them are 55 Mb (in jpg format)
One of the largest and most complete 3D resources with the best free models, textures, tutorials, plug-ins, 3D modeling and rendering software links. Also has its own models and galleries for users