A cross-platform wxWindows class for running Ghostscript and manipulating the image it produces, plus an IDE/debugger for developing programs written in PostScript.
For a PostScript debugger, there is now also an Eclipse plug-in - see http://thomas-fritsch.github.io/psdt/
PHP_Dyn is PHP Extension to help debugging a PHP script.
You can get execution trace of scripts not to need change them.
HTTP request parameter can be printed.
Argument value of the function call and return value can be printed.