GameStop is looking at several new ways to make money, but here's the most interesting we've heard yet: after you trade in your used games, you might be able to walk out of the store with a GameStop-branded cell phone plan. GameStop Mobile is the name of the company's new initiative, according to a new, highly detailed webpage on the company's site, and it seems to be a wireless mobile virtual network operator (MVNO) offering 3G voice, data and text messages by piggybacking on AT&T's nationwide GSM network. While GameStop sells used iPhones, the idea seems to be that you wouldn't buy the phone from GameStop itself, but rather just buy a SIM card and stick it into your compatible GSM device.

According to the website, prices start at $20 a month for a pay-as-you-go plan that costs 10 cents per minute or text message, and unlimited talk and text starts at $35 and up, with $45 adding 100MB of data, and $55 getting you 500MB of data. There's also a 1GB data-only plan for $55 a month. None require contracts.

While it's quite clear the would-be cellular service will use AT&T's network and 850MHz / 1900MHz frequencies, there are a few oddities here and there. First, GameStop held its Q1 investor call yesterday with nary a mention of the idea. Second, the coverage map doesn't quite line up with AT&T, showing a variety of large holes, and third, both GameStop's APN configuration Android app and its pricing plans are dead ringers for good2GO Mobile, another MVNO. We're not sure what the relationship is, or when and where (or even if) GameStop Mobile might launch, but we've reached out to the company for confirmation and more details.

Update: The GameStop Mobile website is password-protected now, but you can see what it looked like in our gallery below.