This deal is done, it was valid on Friday 5/16 only.
This will give you more than $20 in Amazon Coins which can be used to purchase apps and games for Nook color devices (Tablet, HD etc), Amazon Kindle tablets and other android devices in Amazon Appstore for Android.
If you don't already have it, first you'll need to install Amazon Appstore for Android per instructions located here .
Then using your browser "buy" the following 9 applications, all are free. You don't have to install them, they will be added to your amazon library. They will give you 900 Amazon Coins in total, each coin is equivalent to 1 cent, so it will be a total of $9 credit.
PicShop - Photo Editor
Camera ZOOM FX
FireFrame - Digital Picture Frame
Photo Studio PRO (Kindle Tablet Edition)
If you already own any of the above apps, you can still get the 100 coins for it, by deleting it from your Amazon Android Apps library and repurchasing it using the app link above.
Optionally, there's a limited time deal in amazon mp3 store: If you don't mind spending 69c on of the MP3 songs on this list this will give you $3 store credit in Amazon Appstore. If you have credit in Amazon Mp3 Store to cover the purchase the song, then it will not cost you money. Again, you don't have to do that to still get the $20+ credit.
Next, buy Grand Theft Auto: San Andreas using the Amazon Coins (you will use those coins, you will not be charged money, but make sure you are using coins, they may take time to show up!). Again, you don't have to install it or play it, it will be just added to your amazon library. This will deduct 699 coins plus tax (also in coins) from your account and add 2000 coins to your account. If you've purchased the mp3 above to get $3 credit, that credit will be used here instead of 300 coins.
Your Amazon Coint balance should now be 1301 minus tax paid to purchase GTA. If you've purchased the mp3, that balance should be 300 coins more. That's $13 or $16 to spend on paid Nook/Kindle/Android apps in Amazon Appstore!
There's another promotion going on right now on Minecraft - Pocket Edition which most of the time sits on top of most purchased apps. If you buy the app, you will get 350 coins back. You can pay for the app with the above earned coins so the app is going to cost you 349 coins (plus tax in coins), but make sure you are using coins before clicking "buy"! Definitely worth it.
There's no simple link to check your Amazon Coin balance. To check it, you'd have to go to any paid game in Amazon Appstore (like Minecraft) and near "buy" button it will tell you your coin balance. To see Amazon credit balance it's best to go to any paid movie page like this one and click on "Redeem a gift card or promotion code" near "buy buttons.
This is a limited time deal, and the photography apps will most likely be gone on May 17th (at midnight Seattle time), so grab it fast.