I am a Nook Color user as well as a Kindle Fire user. I have some books from my collection on one device, and some books on the other. I had to devise a way to read my purchased Barnes & Noble books on my Kindle Fire. Here’s how to install the Nook Android app on the Kindle Fire.
2. Go to your settings gear and select More > Device and set Allow Installation of Applications to On.
3. Open the Kindle Fire web browser and download the Nook apk file.
4. Open ES File Explorer and navigate to the /sdcard/download folder. The bn.nook.ereader.apk file should be saved there. Tap it to open it, then follow the wizard to install it.
5. You now should have the Nook app listed in the Apps area on your Kindle Fire. Open it and type your Barnes & Noble credentials when prompted. You’ll have access to all of your BN purchases.
Some users are reporting that they are using GetJar to obtain the Nook app for their Kindle Fire. I find the method above easier though.