Is there a way to make QuickLook display a hex dump preview of files for which no other preview is defined? This question has two parts, I suppose.


Is there a way to assign a default case to QuickLook (if no other preview applies, use this one) and
is there a good hex-dump QuickLook preview?
I think you would need two things in order to make this work.
 1.  You would need a hex editor that was tied into whatever black magic Apple is using to provide QuickLook.
 2.  You would probably need to set hex editor as the default application for handling the specific file type...   

In short... no, I don't think you can do it out of the box.