I agree that I really dont want them.... I just wanted to check them out and see if they added anything to the game. And since it does not seem that they are verywere, in every Conan-book, I conclude that they are not an important part of the game either.
Scrolls of Skelos has two prestige classes: The Lord of the Black Ring and The Sorcerer of the Scarlet Circle.
Signs & Portents #9 has The Witchman of Hyperborea.
Across the Thunder River has five prestige classes: The Dancing Savage, The Drummer in the Dark, Forest Runner, Hunt Master and Paramount Chief.
Shadizar - City of Wickedness has one prestige class: The Professional.
Aquilonia -Flower of the West has three prestige classes: The Gunderland Mercenary and Poitainian Knight are reprints from Signs and Portents. Gunderland Pikemen was created for the supplement and is all new.
Messantia - City of Riches has three prestige classes: The Merchant Prince, House Agent and Agent of the Crown.
I think you will find multi-classing to be the best option for most characters. I don't want to see a massive proliferation of prestige classes in the game, but if I see one that might be appropriate and cannot be done without just multi-classing and assigning some variant abilities, then I will use one.