If you've ever wanted to learn a variety of new exercises for specific muscle groups, check out MuscleWiki. It's free, easy to use and even calculates your macronutrients and calories. Created by w0ts0n (notanotherlifter on Reddit), MuscleWiki is a slick, beginner-friendly fitness resource with a clean interface. I really dig the interactive map of the main muscle groups. When you click on, say, biceps, you are taken to a separate page with a list of the exercises that work that particular muscle (in this case, biceps) — complete with descriptions and GIFs. It's not yet very detailed nor has an extensive library, but it offers a good starting point for newcomers.
You can also quickly calculate your calorie needs based on your fitness goal, the result of which you can then plug into the macronutrient calculator for a breakdown of your macronutrients (read this to learn the difference between counting calories and macronutrients). The other neat feature is the 1-rep calculator, which can estimate the maximum amount of weight you can safely lift for one rep without actually testing it yourself in the weight room (a risky manoeuvre).
Overall, MuscleWiki is still a work-in-progress. The creator told ProductHunt users that he is still working on expanding the exercise database with such additions as bodyweight exercises. It's a spiffy start, and in time, could become a great resource. Meanwhile, ExRx.net is a highly detailed, albeit less modern-looking, website for fitness enthusiasts of all kinds to dive into as well.