Six Weeks of Blockbuster Online Trial for free with coupon code groupon. Be sure to select Have a Promotional Code as shown in this screenshot. The trial period then shows up as 6 weeks on the sign-up page. Here is another screenshot confirming the 6-week trial for your reference. Note that you also get 5 in-store exchanges at physical Blockbuster stores.
Originally posted earlier, this is just a friendly reminder. It has also been slightly revised.