This is a little old, but as I came across it looking for something else, thought I'd chime in...
Netbios was a network computer/file sharing protocol used by Microsoft and IBM networks TCP/IP was much beyond the a few research labs. Netbios-over-TCP was a step up which allowed for routing over subnets (strict Netbios doesn't) and a few other features we take for granted when networks span more than just a single office. Netbiosd is part of the the BSD/Linux/Mac OS X implementation of this and is used primarily for talking to Windows based sharing services.
Part of the Netbios specification is that every so often, a computer on your local network (or that can be easily routed to you) sends out a broadcast "Hey I'm Here!" message... this is how you see computers listed when you Browse for local file servers, etc.
Now, I can't say for certain about the public IP addresses listed by some of you above, but I can say that anything in one of the following ranges is considered private (i.e. limitted to behind a firewall and not routed outside of your immediate network):
10.0.0.0 through 10.255.255.255
169.254.0.0 through 169.254.255.255
172.16.0.0 through 172.31.255.255
192.168.0.0 through 192.168.255.255
I've seen a few going out to 10.37.129.255, which indicates that my machine is broadcasting to the 10.37.129.0/24 network that it exists... a little digging, and sure enough, 10.37.129.2 is the IP address for one of my Parallels virtual interfaces... so it is the Mac side of the Parallels network interface that is notifying the rest of my network that it can recognize Netbios information.
Now, if you never access Windows file servers or printers, you can safely block the process entirely and never look back. However, if you do access Windows based network services from your Mac, you may find that you can no longer browse directly to them but have to access them by IP address (smb://10.0.1.4/Files as opposed to smb://WindowsServer/Files, for example). However, you should still be able to share fine. If you can identify your specific local networks (usually in one of the ranges above), you can allow the process for those IPs, and block it for all else, but I'm not sure if LittleSnitch supports that yet (just got it a few days back). I know the built in IP based firewall can be set up to block it adn allow only specific address ranges to work.
So, hope that helps some... like I said, not sure about the 1 or 2 address mentioned above that are public, but thought I'd share.
--
A-Ron
So... it's safe to block and doesn't really