Free. Current App Store rating: 4 stars
Apple's Contacts iOS app is about as basic as it gets. Fortunately, there are plenty of alternatives, and Smartr Contacts is one of the best. You can link your Outlook, Gmail, Yahoo Mail and iCloud email accounts, along with your Twitter and Facebook networks. Once you've done that, Smartr Contacts gives you a "holistic" view of each contact, with email history, including when you sent that contact a message and a list of people you have in common. It's all delivered in an appealing interface, and the initial scan of your data (after linking your email and social networks) is very fast. We'd love an iPad-optimized update with LinkedIn integration, though.