The impossibly gorgeous Amber Heard! (Pineapple Express, Zombieland and DRIVE ANGRY 3D)
Based of this lovely photograph: http://tiny.cc/r8k59
Airbrush, plenty of Dodge/Burn and tool for detail and Sharpen/Blur tool for finishing touches! Worked on this straight over one rainy, flooding weekend.
Also with the help of David Nagel's Photoshop Skin texture brushes