T-Mobile's better-than-average rate plans continue with their new unlimited family plans, which costs $99 for the first line, and $49 for each additional plan after. You get up to four extra lines, but each line has unlimited calling, roaming, SMS, MMS and IMing. The more lines you get, the more cost effective each one becomes, and for a family with frisky parents, this can be a real money-saver. [T-Mobile]