>Disk Defrager - Norton Tools
>ScanDisk - Norton Tools

Actually, the defragger was bought from Norton some time around Dos 5 or 6, but then most of the good features were scrapped. Norton's defragger would leave two blocks on disk: the used, and the unused. M$'s defrag lite would just defrag the files, but never the free space. And all the options to physically sort or group the files while defragging are gone. Maybe some of them still appeared in W98, but not in NT4 or later.

Don't know about ScanDisk, it seems like chkdsk on steroids, it may be also bought from Norton, or imitated, not sure.