one more option: nail polish
when all else fails, nail polish is the perfect touch-up paint! my lbs recommends it because it is strong, durable, waterproof, and comes in lots of different colors! also, inexpensive and easy to apply.
i had a chip in my frame and literally took the frame inside the drug store and the lady behind the counter helped me match it -- like she would any other customer looking for the "perfect nail polish". I was impressed ... she acted like it was perfectly natural for a women to come in carrying a bike frame and wanting to match the color --:D