A couple of nice Skull Tattoos images I located:

Atlas Tattoo Studio bathroom mirror. My Tree of Life tattoo, North Coast Native American Chameleon.
Skull Tattoos

Image by SoulRider.222
12/22/09. Portland. Nikon coolpix S50. Handheld. SOOC.

Sugar Skull
Skull Tattoos

Image by samezzz
My sister have asked me to draw her.