A very cool new utility included in Tiger is Grapher, which draws lovely graphs of equations in 2d or 3d, and does a whole lot more too.
This is z = 1-sin(x)+sin(2y), but there are some much more complicated and beautiful examples in the ‘Examples’ menu:
What you can’t see here is the fact that it’s rotating gently, and you can turn it in any direction you want using the mouse…
Worth investigating.