Friend Book envelopes and extends the iPhone's built-in Contacts app. Divided into three parts, a photo contact viewer and manager, a wireless contact exchanger, and photo dialer, it gives contacts some fabulous new abilities, though sometimes at the expense of quirky new constraints.
Note: I grabbed Friend Book pretty much the instant it was released on the App Store. Since then, it's been taken down to address an issue with contact permissions but should return shortly. If any functionality changes in the re-release, I'll update here.
Read on for the walkthrough, after the break!