In the science fiction movie "Gattaca," Ethan Hawke's character was able to get into a secure area using nothing but a scan of his retina. That technology actually exists today. It's called biometrics. In addition to your eyes, it can scan your fingerprints or recognize your voice. It's a great choice for people with fat bank accounts who harbor government secrets, but for the rest of us, digital door locks offer a cheaper home security option. Digital door locks can be opened with an electronic "smart key" or a remote, or you can open them by typing numbers on a pin pad. These locks are almost impossible to pick.