Food, Inc - A disturbing look at the corporatization of our food supply. It doesn't spend time just trying to disgust you by showing the killing floors and such, and in that regard it probably doesn't show you anything you haven't seen. It's more about how the corporate boogieman issues like cost cutting, government support of big business, and the absurdity of our patent and legal systems are impacting one of the most important activities of our lives. Moreover, it does a good job explaining why it's a bad thing.
It hardly spends any time talking about the dilution of the term "organic", and the end of the film includes a call to buy organic, so it's not very helpful there. It tries to make you feel empowered as a consumer, but ultimately the film may have been too effective at espousing the efficiency of the corporate food machine, as I certainly did not feel empowered by the end.