T-Mobile USA Intros $79.99 Unlimited Everything Plan
Also unique with this is that it includes "4G" coverage, but of course, it's debatable whether HSPA+ is truly 4G or not. The only "gotcha!" is a big one for heavy data users. While "unlimited" data is included, you'll see throttling begin after you exceed 2GB of use within a month. Of course, T-Mobile says that "on average," their customers use but 1GB of data per month, but still, if you know you're one of those that uses more, you need to think long and hard before biting on this one.
The new $79.99 Even More unlimited plan is available now for qualifying customers, so the real question is "what phone are you going to grab?"