OPI, a nail polish brand that I really like, offers a free iPhone app so that you can see all the colours available and then see how they’d look on you. The app has a little cartoon hand that you can try all the nail polishes on. The image of the hand can also be adjusted to match different skin colours. It’s a nice idea, but I find the choice of skin tones pretty limited; especially for non-white people. It’s a step in the right direction, but more choice in skin tones would make this useful to more customers.