In the US, prepaid cellphone service tends to be a like-it-or-leave-it proposition that rarely fits perfectly, especially for families. Virgin Mobile may have a smarter approach in store; it's launching Custom, a prepaid family plan that lets you tailor usage to your liking. You can put as many as five people on plans that start at $7 each ($35 for unlimited talk and text) and scale up depending on individual needs. If Mom is a big fan of streaming music but rarely makes calls, she can pile on the data (or use a $5 Unlimited Music plan) and reduce her voice minutes; a chat-happy kid, meanwhile, can have gobs of messages but only minimal internet access. You can change the plans at any time from mobile apps, and built-in parental controls let you declare certain apps as off-limits during specified hours.