Is there a way of being able to output all the include files use in a web page?
I am debugging someone else's code and they have used multiple includes and sub includes and it would be really handy to see all the includes that were used?
I don't know of any way to get a comprehensive list of included files in any CFM document. However, if you have robust error reporting turned on in CFAdmin, you should get the exact line number of specifically which document caused any errors.
If this isn't enough, you can place code (including included files) within CFTRY/CFCATCH, and use CFDUMP to display the #cfcatch# which should give you all the information you need to troubleshoot any issues.
If you turn on Enable Request Debugging Output, it will list every file processed during the request (including components and includes), as well as how long it takes to process each one. However, you should only turn this feature (or Robust Exception Handling) on in a development environment, as it will reveal internal information about your application.
Most editors, such as Eclipse, enable you to search within a directory or file. Just search for the cfinclude tag. It may help to use regular expressions.