There is a MacTar (or perhaps just Tar) which should be available from 
any Umich or InfoMac mirror (look in the translation or compression 
directories).  Also, if I remember correctly, the latest version of 
Stuffit Expander, in conjunction with the newest Stuffit Engine, will 
both ungzip and untar files.

Of course, the best way to do it is just to use unix tar and gzip from 
the NetBSD side (this assumes you have a working system already, 
though).  Just use the hfs utility to copy the file over from the Mac to 
the NetBSD side and gunzip and untar it there.

Hope this helps some.

Later.

-- 
Colin Wood                                      ender@is.rice.edu
Consultant                                        Rice University
Information Technology Services                       Houston, TX