where do you put prototype declarations?

[William Roetzheim]

  I may be the only one, but I like to put all of my function prototypes
in one include file which contains only function prototypes.  This simplifies
separate compilation and testing and provides me with a ready index of 
the program's functions (and their parameters).  Because my programs typically
have many functions (hundreds), I keep the prototypes in alphabetical order
within the file.

WHR