NASA has most of the images from the missions on a site somewhere in 3MB files that are good to about 8x10. There are 3 companies that are allowed to scan the negatives if you want one of the more obscure images or one of higher resolution.
Originally Posted by Flotsam
We got the picture of Buzz Aldren ("Visor") from one of these companies. They were *very* cool about it, and let us have a high-res version for free. Even after cropping, it was good for a 16x20 image.
Take a look at the original--major tilt. Even the versions normally shown have some tilt to the horizon.