In case of emergency there's ICE Lite
Even if you already have emergency-contact info in your address book (and by all accounts you should), there's no harm in adding this free app to your iPhone.
By now you've heard of "ICE," right? The idea is to add an "In Case of Emergency" entry to your phone's address book and fill it with emergency contacts, important medical info, and the like. That's so rescue workers have an easier time helping you should the unfortunate need arise.
ICE Lite is ICE in app form. It contains just two screens: one with personal info (name, address, phone number, etc.), and one with emergency-contact info.
There's room for your emergency contact person's name, relation, and phone number, along with separate fields for your physician and pharmacy. But that's it. You can't list more than one emergency contact, and there's no room to list any existing medical conditions or medications.
The 99-cent ICE Premium adds screens for allergies and medications, but I still think it comes up short.
What's more, it's debatable whether an emergency worker would ever spot the ICE app, even with its bright red-cross icon, as they've been trained to look specifically in the address book. Granted, you could put a note there directing them to the app, but that seems counter-productive.
Of course, there's no harm in having both. Let's face it, when your life hangs in the balance, there's no such thing as too much information.