During the day if you open it up you can probably reflect the sun off of the display for a signal.
At night since the display can be on for a few seconds you can constantly open and close the phone(my Samsung is fairly bright) and use as a flashlight or beacon-but I'm not sure how far away the light can be seen.I've just used my cell as a flashlight outside the home when I didn't feel like going in to get a real light.