Originally Posted by maxx233
Is there any device that can be put in-line on the beverage line to regulate the pressure coming out of a corny keg?
Umm, how about a soda dispensing valve?
Seriously, they're well suited to the purpose. They have an adjustable compensator that you tweak until there's no foam (at a given dispense pressure & temperature).
Cornelius apparently have a 'slide rule' for pre-mix that will tell you the appropriate pressure for a given ambient temperature & desired volumes of CO2, but I've not seen one.