Here's some stuff I found very useful:
Composition
http://www.musique.umontreal.ca/personnel/Belkin/bk/index.html
Counterpoint
http://www.musique.umontreal.ca/personnel/Belkin/bk.C/index.html
Orchestration
http://www.musique.umontreal.ca/personnel/Belkin/bk.o/index.html
Harmony
http://www.musique.umontreal.ca/personnel/Belkin/bk.H/index.html
All books written by Alan Belkin
Composition
http://www.musique.umontreal.ca/personnel/Belkin/bk/index.html
Counterpoint
http://www.musique.umontreal.ca/personnel/Belkin/bk.C/index.html
Orchestration
http://www.musique.umontreal.ca/personnel/Belkin/bk.o/index.html
Harmony
http://www.musique.umontreal.ca/personnel/Belkin/bk.H/index.html
All books written by Alan Belkin