iOS: PureContact, a gesture-driven contacts manager and speed dialler that was previously Android only, is now available for the iPhone as well. You'll see all of your contacts in a grid arranged by their faces, and you can assign gestures to call, text, WhatsApp or email them.
The Android version of the app is free, but the iOS version is $1.29. Besides the price, the two apps are largely identical. All of your friends are listed by their contact photos, and you can tweak the grid to show more or fewer contacts. You can also perform various actions by swiping your contact's face, so for example a left-swipe can be email, while a right-swipe can be text, and a double-tap can be dial. You can customise those gestures to do what you want.
Aside from that, PureContact doesn't bring much else to the table. If the gestures really draw you in, hit the link below to check it out. If you want something more powerful, Contacts+ for iPhone is a free, more feature-rich option. (Android users: It's also our pick for the best Android address book.)