Digg is a technology news website that employs non-hierarchical editorial control. With digg, users submit stories for review, but rather than allowing an editor to decide which stories go on the homepage, the users do.
Ann Devitt, and Khurshid Ahmad. Proceedings of the 45th Annual Meeting of the Association of Computational Linguistics, page 984--991. Prague, Czech Republic, Association for Computational Linguistics, (June 2007)