Coincidentally, I was just talking to a friend of mine who used to have a detailing business. He now has a beautiful BMW M3 as his daily driver and will be taking delivery of a Nissan GT-R soon. He just ordered something called "Dr. Colorchip". Whereas he hasn't tried it yet, he told me he saw the results of someone else who tried it and said it looked much better than your typical touch-up application. I think the website is drcolorchip.com
I haven't tried it, but the price seems reasonable enough to give it a shot!