Autocompletion in the Windows command processor

Registry key:

HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor (for all users)
or
HKEY_CURRENT_USER\Software\Microsoft\Command Processor (for the current user)

Set
CompletionChar to 9 to have TAB complete file names,
PathCompletionChar to 9 to have TAB complete folder names.

Nuff said.