a fraternity on my campus, Phi Sigma Kappa, got a calendar done and it highlights brothers from their fraternity. They sold the calendars for $10 each and they put their PSK letters hidden somewhere in the photos so you have to try to find them.
It was a hit with the sorority girls, but as far as marketing to the whole school, I don't think they would get many purchases. Our campus has only 2300 undergrad so it's pretty small but I do like your idea of 'selling' space to groups/sports teams to be highlighted in the calendar. good luck!