What is the best Mac program for creating fancy Mac Icons?

I believe Adam Betts does most of his work in Photoshop and Illustrator. And he does amazing work.

And here is a good tutorial on making “aqua” icons in Photoshop.
http://www.iheartny.com/howto_01.html

Photoshop & Iconfactory’s Iconbuilder plugin.

http://iconfactory.com/software/iconbuilder

I use Illustrator for the most part – lots of flexibility, though it takes time to learn.

Photoshop is also great, but start at a large size as scaling up will drop the quality (unlike scaling up in Illustrator which is vector based, so lossless).