Just some samples and ideas of what is possible:
This studio owner raised money for a local humane society and was able to get several businesses involved in an advertising calendar which showcased a different shop each month, the dogs and her photography. She charged $100+ to shops for inclusion of their ad in the calendar and sold calendars in the shops, local vet and humane society for $10-20 each with the proceeds going to the humane society.
Other studios have had success coordinating charity awareness & fundraising. This studio owner incented clients to sell calendars to raise money for her charity by offering photos of client (babies, models etc.) in the calendars. The cover photo was awarded to the client that pre-sold the most calendars.
Others earned free photo shoots, canvasses, prints for reaching different levels of sales. Calendars were then distributed by the clients that sold them.