Q: How can you see all properties of a mail, calendar or task item in Outlook? I'd like to see all the properties of any item in Outlook.  I know there are more properties than get exposed via the dialogs and forms within Outlook, but I don't know how to see behind-the-scenes.  For example, I'm sure a calendar entry must have a created date stamped on it.  
Is there a tool or a secret keyboard shortcut in Outlook or something that lets you see a list of all properties and their values for a given item?  I'm thinking along the lines of ADSIEdit and how it can peek into an Active Directory domain and show everything.  Perhaps there is something similar for Outlook?

A: Try out these two:
Outlook Spy
MFCMAPI

A: For many items you can just choose the fields you want to show.
Your example of finding the date a calendar item was actually created is quite a common one, and is described in this article:
Using Field Chooser to find out when an Outlook appointment was created
