A colleague and I teach a college level syntax- and- style course. We use
sentence diagramming together with sentence combining.  For our diagrams,
we use a space-saving variation on the Reed-Kellog diagrams.  I
learned it  from my colleague.  Instead of of slanted lines for modifiers,
for instance, we use lines
that come down vertically and then branch off horizontally to provide
lines on which to  place the modifiers.  This permits you to stack
modifiers on top of each other.
 
Two queries:
 
(1)  Does anybody know of any computer software that makes it easy to
diagram sentences?
 
(2)  Does anybody know of a form for diagramming adverbs or
prepositional phrases that modify whole sentences, as in "Unfortunately,
he failed the test," or "According to Hoyle, you may do that."  Attaching
them to the verbs seems unsatisfactory.
 
Michael Kischner
North Seattle Community College