At first, I dismissed this as a lightweight system tool, but it turns out this is quite a versatile utility.
You can copy DVDs and create disk images (DMG) files. You can also restore files from those images.
It will check the health of disks (like chkdsk) - I presume it uses something like fsck under unix.
You can also partition the drive and format drives as Mac OS Extended filesystem, MS-DOS (FAT32) or UNIX file system.
[It's not as versatile when you boot the OS X install disk on Intel, see next post]