The link below is a good place to search for a wide range of film posters from a variety of genres, time periods and countries. Has brilliant search features allowing you to search by Directors, Actors/Actresses, Designers and A-Z. Also highlights recent additions.
Year 10 and Year 12 should be looking for films from their genres to ensure your posters conform to codes and conventions. Year 12 must also concentrate on the marketing campaigns of specfic comparable products.