There's tons of stuff to do with a demon, plenty of stock art and graphics to use, I suggest doing a google search for "Ghosts, Tribals and so on style tattoos, another thing you may want to look into is a vehicle wrap, anything done in hi res graphics can be added to a wrap, they are getting more popular these days, just not shiny enough for me.
I like the Old School original, I think Chryslers colors and weird schemes they put together still are classics.