Oh my god -- how I could I ever think that this discussion would
never occur...  But, oh well, I can give my personal contribution,
even I will have to rename the title of it a just little bit:

  "A musician's, arranger's and organ grinder's
   dream of an organ and it's scale"

I have to divide all of this into simple points, as probably nobody
will be ever be able to extract any useful information.  :-)

Point 1:  As a matter of fact, even though there are many songs and
possibilities for it, a normal monkey-organ will never be the perfect
solution.  Why not, you will be able to see as of the next points:

Point 2:  Even though chromatic seems to be luxurious, herein lies the
basic condition for the possibility of everything (!).  To get this in
a harmony with cutting costs is hard -- you will need:

Point 3:  Limitation of the scale -- you can have that as easy as just
taking one octave of everything.

Point 4:  Combining: for taking a standard scale, it has to be combined
out of the ranks available.  For a new scale, decisions have to be made
of how big you want this scale to be:

 - one octave melody
 - 2nd octave melody*
 - one octave accompaniment
 - one octave bass
 - one octave countermelody
 - another octave countermelody*
 *) could be combined together

For MIDI-System every pipe accessible.

Point 5:  MIDI-System also via direct input (keyboard)

Point 6:  Percussion: has to be as "colourful" as already the
assortment of different sound-directions chosen for the different
ranks.

End-Product:  An almost cathedral-sized organ, just portable and with
percussions and other elements not to be found in church-organs; 4-way
(or more) controlled, multipurpose concert organ.

*dreaming*

Well, so much to what I can say about it.  Any volunteers for making
that as a present for me?  ;-))

greetings by(e) InK - Ingmar Krause

P.S.:

Point 6 is about the most important point for building something
very special new.  Point 2 is about all what you wanted to know about
a modern scale.  Point 3 and 4 show how this is made affordable (under
limitation of Point 6 to the contrary, though).  Compacting this is
like the achievement of the MPEG mp3 compression standard: very hard,
but worth it.