[ via MacInTouch
for converting contacts from Outlook Express to Mac OS X's Address Book:
"My mother had a ton of contacts in Outlook Express, and just moved to OS X. Sadly, I could find no easy way of getting the contacts from OE to Address Book. So I wrote one: OE2vCard.html. It's not perfect, but it worked well enough, and I'm putting it out there for others to use."
UPDATE, 09/09/02: An easy way to import contact info from Outlook Express into Jaguar's Address Book? Apple did provide an easy way, though it's not easy to find unless you're looking for it. Go to Library/Scripts/Mail Scripts/Helper Scripts and you will find a script called "Outlook Express".