GPS: What is it you may ask? It's an editor for C programs or extensions. It automates the structuring of a program.
I found that with many projects I would get lost as the project grew. I would start factoring out the code into more files, and then as those files grew, I would again have to restructure the project. I also found it annoying having long function prologues with code. Fed Builder is a simple solution to these problems. It saves source files automatically whenever they are changed using the extension .csrc. It generates the C code for those files automatically on the fly.
Release 13:
Browsable directory: http://www.xmission.com/~georgeps/implementation/software/Fed_Builder/
ProcMeUp is a similar project designed for structuring Tcl programs.