WebMD

Hypochondriacs, beware: For the rest of us, this app will really come in handy. WebMD's popular symptom checker allows you to plug in your symptoms and peruse possible ailments, and it's now available through your phone, along with information on drugs and treatments; a basic guide to first aid; and listings for local doctors, hospitals and pharmacies. Available for iPhone and Android.

Download: WebMD, Free