One of my favorite movies is The Butterfly Effect. Ashton Kutcher plays a character who has experienced a lot of trauma in his life. He discovers by accident that when he sees something from his past, he blacks out and can go back to his past. From there, he is able to make decisions that change the outcome of the future.
Interesting blog post from the NY Times, interviewing the designer that created the famous Obama logo.
Check it out here.