Amazon is running a promotion for Music Unlimited where you’ll get 30 days for free, plus a $10 credit applied to your account after the free trial. The promotion is targeted, but thankfully it’s easy to know if your account qualifies. Those who qualify will see the text “$0.00 per month – The following promotion applies after your free trial: $10 promo credit” displayed on the page. If you don’t qualify, it’ll simply say “The promotion is not valid” in red near the top of the page.