For a pedestrian little program Address Book has a lot of neat features that people often forget about. If you go into the address book and click on on the name tab in front of a phone number you can select "Large Type" and have the number displayed all the way across your screen (see image after the jump). The original purpose of this feature was presumably so that you could display the number on your computer and easily dial it from across the room.
This "Large Type" seems to be built into OS X and so can be invoked in other ways as well. For instance, Quicksilver has "Large Type" as a built-in action for text. So if you invoke Quicksilver, enter text mode with a period (.), type some text, then tab to the action field and select "Large Type" it will be displayed in the same manner. This is surprisingly useful as I sometimes leave messages for other people on their Macs this way, and as we mentioned in a more advanced Quicksilver tip, this can be a great way to give yourself timed reminders.
In addition to Large Type on phone numbers, Address Book has lots other tricks up its sleeve. For instance, if you click on the tab in front of an address you can select "Map of" to open that address in Mapquest in your default browser (see after the jump). As we mentioned a while back, there's also a plugin to add Google Maps to this as well. With the appropriate Bluetooth phone Address Book can send SMS messages and dial numbers. You can even print out a pocket sized address book. If you haven't done so, check out the Address Book help for all these tips and more.