The HTC Droid Incredible will be offered for free from Best Buy.

If you're in the market for a new smartphone, you might want to keep a close eye on Best Buy's latest offer.

The company announced today that through the rest of December, it will be offering at least four models of smartphones for free in its brick-and-mortar stores, online, and in its mobile specialty shops. All four major carriers--Verizon, AT&T, T-Mobile, and Sprint--are included in the offer. The company said it decided to launch the program after enjoying a successful "Free Phone Fridays" campaign in October.

The devices Best Buy plans to offer include the HTC Droid Incredible, the LG Optimus, and RIM's BlackBerry Curve, among others.

But as with most deals, there is a catch. To get a free device, consumers will need to either enter into a two-year contract or upgrade their current line with a new two-year agreement.

Further reading: Holiday smartphone deals and iPad-iMac choices