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.