This thread will simply serve as an easy to access place to find headers that have been written.
Ghost.zh by Saffith
A library of functions creating ghosted enemies.
Tango.zh by Saffith
Functions for displaying messages and creating menus.
FFCScript.zh by Saffith
Functions for running other scripts within an existing one by adding to an FFC in real time.
A series of general purpose extra constants and functions.
Items.zh by SUCCESSOR
Functions for assigning items to A, B, L, R, and the Ex buttons.