File/Print lets you print the Contacts. Perhaps you could print a
group by category view that gave all the categories that were in use.
I don't think that there is a way to print all Categories, including
those not used, from within Outlook.
There is a painfully laborous way to get the list (Credit to "Outlook
2000 in a Nutshell") albeit in form that needs some software or work to
make it intelligible. I know that the method works for Outlook 2002/XP
also. It probably works for most newish versions of Outlook.
Using regedit to access the Windows Registry (Backup the registry
before doing this at home.), highlight the key
'MyComputer\HKEY_CURRENT_USER\Software\Microsoft\Office\9.0[for 2000;
10.0 for 2002, 11.0 for 2003]\Outlook\Categories, then choose File
Export, giving the file an 8-character name (so you could import it
again, say, on another PC). This file will be in hexadecimal Unicode,
I think. On my PC (US) capital letters are 41-5A; small letters are
61-7A; 3b is the separator semi-colon.
There must be some micro-application that would render this readable to
ordinary humans, but I don't have it.