They Know Where You Are

Your computer knows what you did last weekend -- but that's okay because most of your other gadgets do, too. Your browser remembers your Web reading list, your cellphone saved your calls, and your MP3 player can recite the songs you heard. And most of us seem content to have all this sentient machinery memorizing our daily routines, so long as all the data stay with us. A little surveillance of ourselves can be fine if we, and nobody else, get to see the results.