I have been working lately on developing a nice marble texture for use with the VrayFastSSS Shader. Marble does have some really nice SSS that happens with it, and I have been trying to recreate it perfectly in 3d. Before I release the whole material, I thought I would give away the diffuse map I am using. Plug this into any material you like, it should tile nicely. Hopefully this is helpful to someone. I know personally, getting a tileable marble texture has been a bit of a chore. Go here to download the full resolution.