Hey Larry,
""""""""""""" the ability to choose two splines or curves and generate a 3rd one that's in between and/or the average of the two """""""""""""""""

Morph between 2 curves by max, located here:

http://moi.maxsm.net/item/14/category/1

There is also one called a "bisector line" (and also line morph) which may be a bit different (used for finding specific points in layout) here:

http://moi3d.com/forum/index.php?webtag=MOI&msg=3745.52

http://moi3d.com/forum/index.php?webtag=MOI&msg=3745.41