AFN sells cards (they are even available on Amazon), and they also offer a second option. For $10 you can pay to download a disc image that you can copy over to the microSD card you have on hand. This is both faster and cheaper than ordering a card, but no matter which choice you take the destination will be the same.
I know, I know, this isn't the first company to offer this kind of service. NFA is the second to do so and that means that we now get to see them compete on price, quality, and support. That is a win for the end user.
Both AFN and N2A cards will turn a locked down Nook media device into a real Android tablet. It will be running a version of Android 4.1 based on the work of the open source CyanogenMod project. Along with the OS you'll get Google Play, the ability to install apps which weren't pre-approved by B&N, and access to more sources of content that far exceed B&N's paltry app store and ebookstore.
Has anyone tried AFN? What did you think?