Many empty-nester parents would like nothing more than to hear from their kids every now and then. For them, Skype's new gift cards might be the perfect not-so-subtle clue: both digital and physical cards are going on sale today that offer $10 or more in credit, either for the company's time-honored VoIP calling or (if need be) some Skype WiFi at the airport. Only online versions are customizable, although Americans who want something tangible can swing by the
