"Right now, our map of the Milky Way still has large areas marked 'Here there be dragons.' Ten years from now, those areas will be filled in," said Mark Reid, of the Harvard-Smithsonian Center for Astrophysics. - Universe Today
A realistic rendering of a two-armed Milky Way is to be had at Astronomy Picture of the Day in lovely mouse-over format, or the originals at the Spitzer Space Telescope site.
Somewhere on the TODO list is to make the map look something like this in Candy style when you zoom out all the way.