With photoshop you can manipulate bitmaps to make them more Eagle friendly by adding a hard mix layer with a halftone over your image. The dodge and burn tools can then be used to tweak the level of detail. Here’s an example from a Data’s head PCB that I’ve been working on http://i795.photobucket.com/albums/yy232/smolder_bucket/datashead.jpg. I also like using polygons for drawing since, unlike bitmaps, they can be routed through.
Just last week I got my Sparkman boards in the mail (dunna da da!) http://i795.photobucket.com/albums/yy232/smolder_bucket/DSCF3553.jpg.