(Disclosure, I may receive a small referral fee when you make a purchase through links on this post.)
If you own a Chromecast, Google is giving away $6 in Play Store credit for movies, music, or apps. All you need to do is go to this url in your Chrome browser: https://cast.google.com/chromecast/offers/
You do need to agree to allow Google to check your device ID with them to search for available offers. I was able to find other offers from DramaFever, epix, 90 days of unlimited play music streaming, and the X-Men movie also!