Art modeling is posing for artists, usually nude, so that they can practice drawing the human body. There are figure drawing classes at schools and universities, as well as for private drawing groups.
Art modeling can be a part time or full time job, is very flexible, and usually pays $15 - $20 an hour. I'm Aaron, and I've enjoyed modeling for artists for the last few years. I wrote the e-book Art Modeling Mastery to show people how to start art modeling.