Paraview

Paraview is a great free tool to visualise large data files. It works well for parallel applications and it has a very good server/client interface: the large data can be processed remotely on a server, and the client will only take care of the visualisation. 

It is installed easily, being a universal binary. If you want the server/client facility, you will also install the unix commands provided. Please read this post to change the paths according to the new Leopard paradigm.

On goofy:

•  unix commands under /usr/local/paraview/paraview-3.2.1-Darwin-i386
  
• path updated in the file /etc/paths.d/Paraview