In addition to trying to finish my next screencast, I've been helping my wife get our Christmas cards done. One such task has been getting the address list together. For this I generally use Address Book. This year my wife had a word table with some new addresses and friends for inclusion on "the list." In order to make getting this data into AddressBook, I used Pages to convert the table to text and then I emailed the the list to myself in the body of an email. I then used Mail.App's quick entry to add them into the AddressBook database.
I then simply went through and added an entry for "Holiday Card" on all of our friends and family.
Once that was done, I made a smart group that included a search for Holiday Card.
Finally, I set it up to print on Avery labels and Christmas was saved.