i found this the other day while testing an old DOS norton disk editing utility. you can browse the files in each block of each cluster, and modify the name and other attributes of the file. you can scroll to the specific file or folder and delete all the characters in the name and the disk will save the new name as having no characters, which is against windows' "laws". you will be unable to see the file at all in the win98 GUI and cannot access or modify the file in ms-dos or windows.

NOTE: Only tested on computers running Windows 98 SE - MS-DOS 7.1.
I imagine it will work on any FATx filesystem.