iOS/Android: MuscleWiki is a free fitness resource for beginners that started out as a slick-looking web app. Now you can easily search for and learn about muscle-specific exercises, figure out your calorie needs and calculate your one-rep max even when you're not at your computer. As you'd expect, the free mobile app is the pint-size version of MuscleWiki. Like the web app, you point at a specific muscle on the interactive model to bring up a not-quite-definitive list of exercises that help work that muscle. Since we last introduced MuscleWiki, they have added a female-looking model which lead to a separate list of exercises for the same muscle group. I'd like to point out that those exercises can be done by anyone.
If you're just getting into weight training, MuscleWiki helps open your world to a myriad of exercise options while you're at the gym. However, some of the new additions to the MuscleWiki web app, including stretches, aren't yet available on the mobile app.