Straight Talk offers a nationwide plan for $45 with unlimited minutes and text messages, but with only 30 megabytes of data for data-enabled phones. That price doesn't include taxes and is only for up to 30 days of service. You can then refill the plan after 30 days.
If you don't want to go unlimited, Straight Talk also offers a $30 no-contract plan with 1,000 anytime minutes, 1,000 text messages and 30 megabytes of data. The carrier's service coverage map can be found here.
Straight Talk only sells three cell phones at most Walmart locations (with more online): the MOTORAZR V3a for $99.99, the Motorola W385 for $79.99 and the LG 200 for $29.99. You can keep your existing cell phone number from another mobile carrier or pick a new one.
Straight Talk is a registered trademark of TracFone Wireless, Inc., which the company says is America's largest no-contract cell phone provider in the U.S. with more than 11 million subscribers. TracFone, which was founded in 1996, is a subsidiary of América Móvi. Straight Talk phones are sold at Walmart stores.
What plans compete with Straight Talk? Prepaid carrier Cricket Wireless offers unlimited talk, texting and data for $45 a month, but it doesn't include nationwide roaming.
Boost Mobile offers an all-unlimited plan for $50 per month. Virgin Mobile also has an unlimited plan for $50 a month with no contract or roaming fees, but that plan doesn't include data or texting.
For a prepaid monthly price comparison, see this visual matrix from PlatinumTel.