Sure can and it was possible on all versions. In the Contacts Folder, turn
on the Advanced Toolbar and use the Field Chooser. It has a New button that
enables you to make new fields.
I use new fields in a table view eg Phone List.
Regards
Judy Gleeson
MVP Outlook
Trainer and Consultant www.pragmatix.com.au
My suggested settings for Outlook 2003 are FREE on my website.