I remember seeing a program that used something else once, and when I worked in web apps and websites, there was always a debate about what to use.

A common one is a folder icon (or a tray) with a download arrow... DESPITE it being used to save locally. Same thing with a cloud with a down arrow.

Some other programs used to use the icon for a hard disk, the three circular platters.

If I remember the app, Ill give better examples of programs that use other things.