I have just visited China (Beijing).  There I had Peking Duck which was wonderful. They served it with a sauce - sort of sweet, brown and thick. I was wondering if anyone has a name for this sauce as the people I was with did not know the name.  I really loved this sauce and want to use it with other things - any help on its name would be great! 
Traditionally, the sauce combines several ingredients, one of which, as Bart mentioned, is Hoisin sauce. The other ingredients are:   Sesame Oil Hoisin sauce Dark sugar or honey Water Dark soy sauce. Cornstarch   You can usually buy this at your local Chinese supermarket, but it's easier and more tasty to make your own. 