This code snippet does the following:

1. Retrieves all hooked-into WordPress functions
2. Displays a list of them on a specific page (private page)

I came across this snippet from Rarst.net on listing hooked functions in WordPress. It’s a great little snippet for debugging, testing or developing. I’ve added a bit of code to the end of it to display the hooked functions on a specific, private page. To use it, paste the code into your functions.php and replace the page ID on line 55 with the ID of your own private page and the hook function name on line 57 (remove the hook name to display all hooked functions).