I've released a black and white "base image" of the Milky Way Galaxy under the Creative Commons Attribution license.
Image is 6MB, too large to attach here; but you can find it on my blog: http://enderra.com/2012/02/01/milky-galaxy-black-white/

Enjoy!

1/8th small-scale thumbnail "preview":

Black & White Milky Way Galaxy, cc-by-galaxy-b-3-neg-released-cc-1024x1024.png