This is the back side of the Battlestar Galactica Currency 1000 cubits note.
I'm have a ton of fun coming up with designs for these!
Adobe Illustrator CS3
Update: Edited the portrait to give it a more engraved look. Instead of using an engraving plugin I opted to try a new technique I learned from a Computer Arts Magazine tutorial. It takes some tweaking and trial and error but the bitmap/halftone mode works pretty well. I'll have to play with it some more. This is my first try and it came out better than the stamp look I had before.
Update 2: I reworked the portrait for a better engraved look. I think I have the method down so I can start on the Pegasus back.