Even better, I created a Service for the Finder. This allows you to right click on a file or files (no folders) and convert them to BinHex.

On my public iDisk, there is a workflow called "BinHex". Open it in Automator and do a "Save as" and name it what you like. The default just says "BinHex" and will show up at the bottom of your contextual menu when you right click.

I think this only works with Snow Leopard, so I'll leave the "BinHex Prompt" application up there too for Leopard users.