I didn't know this about the Green Bay Packers -- or that the NFL has since banned similar ownership arrangements:

The Packers are owned by the fans, not a wealthy owner operating with a profit-at-all-costs (PAAC) philosophy. The Green Bay Packers are a publicly-owned non-profit with a unique stock ownership structure. Green Bay’s bylaws state that the Packers are “a community project, intended to promote community welfare.”[1]

[1] http://www.leagueoffans.org/2012/04/06/green-bay-packers-own...