Add Plot Keywords. User can thumbs up if agree. Info taken from www.themoviedb.org
On TV Show/ Movie information pages you can add a list of Plot Keywords. For Example: post-apocalyptic , superhero , future .
This information should be available from www.themoviedb.org
I would think it would be cool to also add a user thumbs up for each keyword on the info page. So the users can decide which keywords fit the best from themoviedb list. You can then show the more favored ones differently then less thumbed up ones.
Potential for spoilers seems too high for this.