Is there a utility out there that will show me all includes

Real Programmers don`t comment their code. If it was hard to write, it should be hard to understand.

However, your quest is appropriate and when working with Drupal I would sometimes like to know which files were accessed for a given spider-friendly URL.

For one thing, it depends on what those includes contain. If they have just straight code which is run at the inclusion point, you may have to do something tricky to figure it out. However, if the includes (or requires) contain function definitions, you might be able to do something. You`d want to know which include files contain each function. However, to find out how many functions are available to the running script, you can use:

http://php.net/get_defined_functions

and look at the "user" part of the array. For example:

$fn = get_defined_functions();
print_r($fn[`user`]);

Other useful functions for this sort of project would be:

http://php.net/function_exists
http://php.net/get_defined_vars
http://php.net/get_defined_constants
http://php.net/get_declared_classes

You could use the auto_prepend_file and auto_append_file in php.ini
(http://us3.php.net/manual/en/ini.list.php) to write bits of code at the
beginning and end which note any changes to the available functions, classes, variables, etc.

This still does not get you to knowing which files were included or required in your running page, however.

It might be possible to replace each instance of require(), include(),
require_once(), include_once() with your own custom functions that will register the file names in a session variable or database table. I`m not thrilled with this idea but it will depend on how deep you want to go into this.

On a Linux system I`d probably write a script (perhaps in bash) to scan through the PHP files and look for include or require functions to try to trace them.  Of course, such a script probably would not be smart enough to know if one of these calls was inside a conditional or loop structure so they might not apply to the runtime program.

I don`t know if PHP has any internal accounting of included files. If someone else knows of one, it would be interesting to learn about.