FitStar Yoga (Free)

Yoga apps are a dime a dozen these days, but it's not exactly convenient to stop mid-pose, pick up your phone, and make sure you're in the right position. FitStar Yoga's app for the Apple Watch displays the pose right on your wrist, so you can see at a glance if you're getting it right. You can also see how much time you have left of your workout and control the session by pausing or rewinding.