How do you get people to know about your film? To want to see your film? For a film to work we have to get the word out well beyond the film community. Whatever the content of your film there is a community who has a direct relationship to it. Where do they live? What else are they talking about?
Movie Marketing Madness and ReadWriteWeb each have had good posts on how to find the top blogs regardless of the topic. So now you can go out and find those folks and start talking. Get them talking about your movie.