I'm not familiar with MediaMonkey so this may not be an option but...
I've used Subsonic for a number of years as my streaming server. I don't use tools to manage my files but one of the things I really like about Subsonic is that it will present the local file system structure to the clients (rather than only relying on ID3 tags). So if I create a directory called "1990s" it will show up in the Subsonic hierarchy (eventually - it scans periodically for new files).
I'm assuming you could use MediaMonkey to manage the files on your NAS over CIFS? Then Subsonic could just read the filesystem over NFS as well and serve what you have setup.
Subsonic clients offer the option to cache files or stream as well which is great for traveling.