I've just uploaded a very simple IGC file viewer application for Mac OS X
to:

http://www.carrotworks.com/

It has exactly three features:

1. It's a native Mac OS X app that should work on Tiger, Leopard and Snow
Leopard on both PPC and Intel architectures.

2. It plots the geographic trace of a flight onto a map.

3. It doesn't cost any money.

It's very much a work in progress, so don't expect it to be able to plot
climb rates, altitude data, tasks or airspace because at the moment it
doesn't.

Regards,

Richard