If you need to add a field to someone's contact card—such as "spouse's name" or "nickname"—there are a couple of ways you could go about it. First of all, you could add that field only to a few specific cards and leave the template alone. Do that by selecting someone within the Contacts program and then going to Card > Add Field.
Pick something from that list, and it'll be ready for you to type into your selected card.
If you'd like, you can also click on the new header (indicated by the arrow above) to label what you're typing in properly. If the field you've added is "Related Name," for example, you can change "spouse" to "assistant" (or to whatever relationship you want to remember).
If you click on the header and choose "Custom" instead, you can type in anything you want to use for that field.
Great, but how do you add something to the template so that you won't have to do that for every single card? It's easy as pie. Just go to Contacts > Preferences, click on the Template tab, and then click on the Add Field drop-down.
Pick whatever you want here, and any fields you add will be available in all your contact cards. (If a choice is greyed out, it's on the template by default, and you can't remove it.)
One of the neat things about this is that you can click the green plus button next to a template field to add additional instances of it by default—so if you'd like one related name to be listed as "spouse," for example, and another as "assistant," you can do that all simple-like. Once you're finished, you'll have those brand-new fields waiting for you in all the cards you've got.
And you'll never have to be non-creepy again! Why, you'll remember everything, from cats' birthdays to graduation dates! You'll be great fun at parties.