A startup creates a physical keyboard for touch-screen devices, like smartphones or tablets, that appears when you need to type and disappears when you're done. A few weeks ago, right before the new BlackBerry 10 phones were announced, I dragged a cameraman to San Francisco's Financial District during lunch hour and asked random strangers to name BlackBerry's best feature. Care to guess what the results of my highly unscientific poll were? Even iPhone and Android users agreed -- the famed keyboard is BlackBerry's top trait. Increasingly, we "mobile device addicts" are favoring our smartphones and tablets over our traditional computers...