FinalCD is a sample rate converter made by Sonic Illusions. It has gained some popularity among mastering engineers due to its very high quality filtering.
Finalcdosx provides a way to run FinalCD, which is Windows only, on Mac using Wine.app. The script also provides a (very) basic GUI to select the file to convert and to set the filter parameters.
See this blog post for more details and installation instructions. You can find the project on GitHub as well.