Medscape This is actually the app used by healthcare professionals. Awesome medical information and news at your fingertips, much of which is likely beyond most of our needs, but really cool to have nonetheless.
WebMD for Android Love this app for finding quick information on symptoms, causes and treatments. It's also helpful to check drug side effects and interaction warnings. All this plus first aid tips, local healthcare providers and the ability to personalize your listings.
Epocrates Ever have some old pills lying around and you're not sure what they are for? Or you need to figure out the drug side effects and interaction information? Then this is your app, also used by professional pharmacists.
iTriage Health iTriage will be a handy tool for you, especially if you have children. It's great to get advice on what to do in an emergency and what type of treatment is necessary.
Medical Dictionary Ever wonder what the heck the doctor is talking about when giving a diagnosis? This is a helpful app for just that. No more wondering what "malignancy" means! Ha, also great for medical students.