If you have been saving up for an Android-based smartphone, you could potentially save yourself some money courtesy of Best Buy. The retailer is offering Google’s Nexus S smartphone for free today through select Best Buy outlets.

Customers can purchase the Nexus S at any Best Buy, Best Buy Mobile specialty store or online at BestBuy.com/Mobile for free with a two-year service agreement (of course!). The deal is valid either as a new phone purchase or an upgrade purchase on AT&T, Sprint and T-Mobile networks.

T-Mobile was the first US carrier to offer the Nexus S last December. The Samsung-made handset debuted on Sprint’s network on May 8 and finally found a home with AT&T last month. Perhaps the most exciting of the three is the Sprint 4G version that works with the carrier's WiMAX network.

The first mobile phone to ship with 2.3 Gingerbread, the Nexus S is no longer on the cutting edge of smartphone technology, but it does still feature some pretty cool technology. The Nexus S features a 1 GHz “Hummingbird” Cortex A8 processor, 16 GB of iNAND flash memory and a 4” Super AMOLED display touting a resolution of 480 x 800.

The Nexus S also features a NFC (Near Field Communication) chip which works in conjunction with Google Wallet. This service allows the user to make purchases at stores with their phone by simply tapping the device on the designated payment station during checkout. Google Wallet initially started in beta in large US cities but a quick check of my area code revealed no less than 10 locations within a 10 mile radius of my home that utilize the service.