As one of its daily deals, the Amazon Appstore offers SeekDroid for Android for free. That's the lowest price we could find for this anti-theft app by $5. Click here for more information on its security features. Deal ends today.
Amazon Appstore offers downloads of CastleVille Legends for Kindle with 110 Amazon Coins (a $1.10 value) for free. Assuming you'll spend the coins, that's $1 under what Google Play charges for a version compatible with all Android devices.
Amazon Coins can be redeemed on eligible products in the Amazon Appstore. Note that promotional coins will expire on the last day of the month one year after they were acquired.