Another interesting feature of NTFS file system is alternate data streams, which basically means that a file may be attached extra data such as for example “slave files”. The tricky peculiarity is that data streams are almost invisible to Windows shell, though Windows uses stream to attach version information (Summary property page in file properties) and zone information to mark downloaded files from unsafe locations.
The idea I thought about was that alternate data streams may be useful to create a named copy of file contents, something similar to checkingin to version control system. The idea does not seem to be worth implementation though as it is unpredictable how software (such as word processors) is updating the files. If the file is re-created, the existing alternate data streams would get lost with saving of the new content.
Additionally, a good introduction into NTFS features, including hard links and streams (I am actually surprised I came across these only now):