So, I was using Pages to write a personal letter from the built-in template, and I was thinking "why doesn't the media viewer also bring up Address Book entries?" So on a whim, I decided to try dragging an entry from Address Book to the letter, and wouldn't you know it, Pages understands it: It automatically puts the address information into the correct area. It even populated the salutation correctly.
Yup, I am sure this is RTFM material, as it has to do with being able to insert Address Book fields into a document for merging, but if you are an infrequent user like me, this is awfully nice to know.
You can also right-click on addresses and tell the document to use the Work, Home, or Other address fields.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20070315103904443