The mount plugin allows you to mount devices such as hard disks, CD/DVD-ROM and network filesystems listed in your /etc/fstab and to also unmount currently mounted filesystems. You can specify custom commands for the mount/unmount operations, eject CDs, run a command after a device has been mounted (for example, exo-open to browse it in your file manager), and finally you can quickly see how full a filesystem is, and whether it's already mounted.