The other classic from back then was Fugue: https://p.yusukekamiyamane.com/

Skeuomorphism died a rightful death but good lord could people design a good icon back in those days. My personal favorite designer of that era was Jonas Rask: https://iconarchive.com/artist/jonas-rask.html

You'll still occasionally see his icons pop up in TV shows and movies when they need to show a macOS-like design.