For those who hate the gym, Lifehacker has a standout guide to getting fit without the iron.
Essentials: Circuit style training with an emphasis on squats, push ups, pull ups, dips, a variety of core exercises, and some cardio.
Most people can probably come up with such a workout on their own, but this article goes much deeper than a list of movements. There’s magic in the details. Numbers are key here, and you should definitely check it out.