If you like to draw, wish to draw people, and want to use dynamic poses that most live models can’t sustain for long, there is a very useful website called Posemaniacs (http://www.posemaniacs.com). There are a plethora of images of (clothes-less, skinless) men and women in various poses; these images can also be rotated. Plus there are timed images, negative images, images of hands, and many other options. A donation is requested, but not mandatory.
Here is a sketch I did based on a Posemaniacs image: