Well, if you're not too worried about it being super high quality and are going to go the beater RG way, here's something I did way back when that was lind of cool. I was inspired by Steve Vai's "Playboy" and Little Annie Fanny Comic Strip guitars (can be seen here, I don't want to link pics because there's nekkid ladies:
http://www.jemsite.com/jem/model/perfomance.htm ).
So anyway I started taking all kinds of different things like magazine pics, comic strips, photos, stupid advertisements - anything in print - and did a few different bodies just goofing around. I think just would spread glue over body where the picture was going, making sure not to put too much to saturate the paper, and then glue it to the body. Then, when I had what I wanted on there, I just rattle can cleared over it lightly so I didn't really have to sand it, but the paper would be protected from sweat. Cheap and easy, and kind of cool looking, but not great quality by any stretch of the imagination. That's a thought if you want to just go with something cool and unique but not go overboard on spending (or quality...).