I found a great website describing how to set up a filesystem on one Linux machine that is, in actuality, located on a completely different machine.  This is great if one machine is short of space and you need to load files onto it via, say, a mounted SDLT tape drive.  The files will be pulled off the SDLT tape drive and directed to the mounted filesystem on the other machine (which, hopefully, has more space on it).  Here is the website: Linux NFS HOWTO