T-Mobile now offers Unlimited Talk/Text and Web
(no long-term commitment) for four lines for $100 per month
. That's $25 per person and the best unlimited plan we've seen from T-Mobile for four people. This deal includes 500MB of high-speed data (with throttling after 500MB).
Of note, other unlimited plans are available for $50 for one line, or $80 for two lines.