Once we're done with the basic construction of our bunker, this could make an excellent finishing touch. GE's "SmartHome IntelliCorder" is touted as an "intelligent surveillance system," but we like Popgadget's description better--"a video peephole for your front door."
The IntelliCorder automatically records images of whoever comes calling, friend or foe, but its motion sensor ensures that the video runs only as long as the person is there so you don't end up with endless footage of your doormat and potted plants. And if any monkey business ensues, the video can be transferred to a storage card for future use.
Even if you don't need to record anything, the color screen will give you a better picture of your visitors--especially those who like to stick their eyeballs right up to the peephole. (You know who you are.)