I read about this in a recent http://www.artistsmagazine.com article and I thought it sounded like a good idea: people get together and draw each other. The blogsite that is encouraging the swapping is run by an artist named Rama Hughes at http://www.theportraitparty.blogspot.com.
Artists at all levels of training can benefit from this concept. At a recent workshop, Bill Whitaker suggested this idea to his class: line up an artist friend and set a timer for 30 minute intervals: you paint your friend for the first period and then your friend paints you. No expensive models, no long model breaks.