There's an unlimited number of unlimited plans

The good news is that, after years of having to pay per gigabyte, unlimited plans are now the norm at all of the major US wireless carriers. The bad news is that, somehow, those same companies have managed to create different categories of unlimited. At the low-end, some have data caps before speeds are throttled. At the high-end, many come with premium video services (the latest battleground).

AT&T: The biggest challenge with AT&T's unlimited plans is that the options and combinations keep changing.

Sprint: The nation's No. 4 carrier, which is in the process of trying to sell itself to T-Mobile, has been experimenting with all kinds of promotions and offers, though most are limited-time plans.

T-Mobile: T-Mobile's plans are probably the simplest to understand.

Verizon: In its latest ad campaign, Verizon actually boasts about the fact that it now has a bunch of unlimited plans and you can now mix and match them within a family plan.