What I'm trying to do, is find a way to list all of the files that are in a directory (and sub-directory/ies) that do not match certain extensions.

I know that $findfile will list those that match, so I guess I'm sort of looking for the reverse.

ie: $findfileexcept(c:\music,*.mp3;*.wav;*.ogg,0,echo -a $1-)
would return a list of files that are in c:\music (and any sub-directories) that don't match the listed extensions.