Thought I would throw out a few titles that I felt were some of the better pastiches added to the Conan mythology. In addition I've include a few breif thoughts on what they might be aable to add to your game.
Conan The Rebel, by Poul Anderson.
An extension of the adventures of Conan and Belit. This provides some background on Belit's life and add a good bit of information on life in Stygia. I'll be using it for the details on the city of Luxor.
Conan The Swordsman, by de Camp, Carter and Nyberg.
A collection of short stories, none adds any great detail to the overall vision of the Hyborian World. However, as these are hard to find stories and each is a filler between the material of the Ace/Lancer editions, they provide good concepts that can be developed into one off adventures.
Conan The Liberator, by de Camp.
This pastiche details the rise of Conan to the position of king. Good material for running members of an army, it can also provide information on how to handle overthrowing a kingdom. Also, the secondary story provides good ideas on how to have a evil magic user corrupt a king.
Conan and The Spider God, by de Camp.
Need some information on the politics of small cults and how they can influence a town? Want to know how to base a belief around a monster? Need to throw a wammy at your players? If you answered yes to any of these questions, then this book is for you. It can provide a good background for any cult or belief that you want to create for your game.
Conan The Road of Kings, by Wagner
While CTL is good for using armies to overthrow a kingdom, this book is good for showing how a small group can sow confusion in a capital and then use the cover to assinate a king. In addition this has some of the better betrayels that I've read. Also, it does provide some good details on life in Zingaraand how to set up a rather gruesome form of execution.
Conan The Manhunters, by John Roberts.
If you want to give your players a chance to pull off the greatest robbery in history, read this book. The detail on combining magic and stealth is wonderful. Need to create a NPC group to give your players a run for their money? They are in here too.
All of these books can currently be found on amazon.com and amazon.com.uk. Good luck and remember, the job of a good GM is not to kill off characters. It's making their lives a living hell.