Daily Yoga - free to download for iPhone, iPad, Android
WebMD Pain Coach (iPhone/iPad free)
Information, articles and advice for those fighting chronic pain conditions (primarily back and knee issues). There is a lot of inspirational/motivational push notifications that are helpful without being annoying. I personally used it for months to complement physical therapy sessions for a back condition I had. This is one of a handful of WebMD-branded apps for iOS and Android devices. All free, others focus on allergies, parents with newborns, and general medical/health.
Drugs.com Medication Guide (iPhone, iPad, Android free)
Targeted to patients, this is a comprehensive and easy-to-navigate resource that includes information about thousands of different prescription drugs, their effects and interactions. Users can also upload personal medical records, and ask questions to health professionals.
Fooducate (free iOS and Android with paid options)
Explains what exactly is in the food you eat and how it effects you. Assigns nutrition letter grades to thousands of products, and tells you about healthier alternatives. Use the app to scan barcodes in the store to get calorie counts and other nutritional information.