NBFW is a smb forwarder. With the Samba NetBIOS forwarder, nbfw, you can browse the local windows network transparently to and from your masqueraded network.
This will most likely be of use for people who have Windows machines on a backend network who want to browse the Network Neighbourhood on the 'normal' network though their masquarading firewall.
If your Samba is not working ok, NBfW will not work, too. NBfW can cause major problems if you don't configure it correctly. And it has ... It really helps to know what you're doing.