Let me first say that I am completely blown away by how much awesomeness is contained inside the Shadow Sword Fight video. Japanese tech group TEAMLAB created this video, starring Taichi Saotome fighting against a shadow samurai.
The effects in this video look as good as anything you're going to see on any anime or movie. The shadows constantly change shape around Saotome, forming into everything from birds to monsters. The Shadow Sword Fight video definitely has to be seen to be fully appreciated. Check it out here.