I am not if it's right place, but some of you can find it useful - I am helping my friend to publish her collection of pictures/textures which you can use for free (create tiles, materials etc.). Site is brand new but is very promising - you can get 1500 x 1000 px texture for free without sign-up, and total number of textures is growing very fast: around 500-700 per month of new textures.
So if you're interested please check it out and visit Texturify.com