I'm releasing some animated 3D renderings of ML runtime
environments that I made last summer:

http://perso.wanadoo.fr/pascal.brisset/visu-ml/visu.html

That's definitely useless (although this might change with the
addition of type information, or an interface with ocamldebug)
but I believe the pictures give an interesting view of what's
going on inside the bytecode interpreter.

-- Pascal Brisset -- pascal.brisset(at)cnet.francetelecom.fr
   (not speaking for my employer today)