This falls under so many categories. MacOSXHints has this storyAn AppleScript to look up NetBIOS names. but Real Men use the Terminal. Here's the command line bit that does the real work:
nmblookup -T -U <WINS server IP> -R <NetBIOS name>
Here's an example for work and its output:
cwcx% nmblookup -T -U 128.151.209.155 -R esmdc
querying esmdc on 128.151.209.155
esmdc.esm.rochester.edu, 128.151.209.155 esmdc<00>
In this case I used the WINS server to look up the WINS server's NetBIOS name.