Actually, what prompted me to upgrade my system recently was Sweet Home 3D.

Sweet Home 3D: an interior design application
Screenshot of Sweet Home 3D

This is a Java application suggested on ILUG (pointing to as a tool to help design floor layouts; other CAD-like applications were recommended too but this one seemed to be exactly what I wanted - just draw simple floor layouts with or without furniture. And as an  added bonus, it creates 3D walk-throughs for you as well. Cool indeed.

Problem was, although it would startup on SuSE 11.2, it whinged bitterly about some GLX library that did not fully support ATI cards in  its 1.2 incarnation. Upgrading my SuSE provided v1.3 of the particular  library and right now I am happily making 3D plans or our house, the  office and a rather futuristic Work-in-Progress that Kevin McCloud will definitely want to see!

Of course, being Java, it will also work on Macs.