JRiver Media Center can manage PDF files. Under Tools/Options/General/Features make sure that "Data Support" is enabled. Then any data files (DOC, for example) will appear in the tree on the left under Data.
Under Filetypes, PDF files are under Data/Acrobat Reader.
A thread on Interact: http://yabb.jriver.com/interact/index.php?topic=68025.msg457812#msg457812