I also tried a card from , which offers a choice of three Android ROMs: CyanogenMod, MIUI, and PhireMod. Mine came with MIUI running an iPhone/iPad theme (one of many available), and dang if my Nook didn't look like a baby iPad. Really, really cool.

Prices start at around $35 for an 8GB card; both shops offer a 16GB version for around $50, and N2A sells a 32GB card for $89.99. Bear in mind this is something you can do yourself, using your own much, much cheaper microSD cards (Newegg, for example, has a couple 16GB cards for under $20)--but it's a hassle, especially if you don't know what you're doing. The pre-made Android cards offer plug-and-play simplicity--and the results are just plain awesome.