Website for getting bike-specific touchup paints? A while ago I came across a website that did touchup pens for a catalogue of old bikes, but I can't seem to find it now. I have a specific old bike that I want to check if they have, before I go to the auto-shop.
Gunnar bikes have a selection of touch up paint for classic bikes. 

They also have great information on how to use it, and what results can be realistically expected. :)

http://gunnarbikes.com/site/order/touchup/

ColorRite also has a wide range of paint touch up pens available. 

http://www.colorrite.com/product/touchup-pen-primer-1071.cfm