[CentOS] how to automount usb drive

I have a server with no desktop - just cli that i need to have a user
plug in a usb hd and would like it to automount to a consistent
directory so I can schedule a backup.  The user can rotate the usb
drives and it all just works.

Any ideas how automate so that say /media/backup mounts to any usb
harddrive and unmounts cleanly?

-thx
bazooka