If your looking for suggestions...
If your looking into custom mirrors, also look into custom grips. Mirrors are all preference. It's what you like. And remember you get what you pay for! I bought a pair for $49 off ebay. they lasted half a summer and one broke of riding down the road. (I still run just one, gives it the chopper look)
Screamin' eagle makes colored spark plug wires that catch an eye $12.95 from Harley.
Derby cover
change the stock rear pegs, maybe put a custom shifter peg on, they make some really nice ones for not all that much.
If you want to stick with the skull theme... One thing i did and it turned out really cool. Any auto parts store carries them, they are for the trailer hitches for trucks when the hitch is removed, follow me? I found a skull one and the eyes lite up. I installed that above my oil cooler, there is a cross member support on your frame with holes already drill in it (not sure why this is there) But with a little mod you can mount it and wire the lights to the battery so it lights up. I've had many people ask where i bought it, or where they can find one. If you check out my pic's on here you can get a good idea of what i mean.
Neon lights are also an easy add one, and it is legal to lite your engine compartment in Mich and many other states. But be careful, some colors are still Not legal.
http://www.hdtimeline.com/members/caseydeuce-albums-motorcycling-picture1559-a.jpg