Amazon is emailing some of its customers with an offer to try out the $99 Fire TV box free-of-charge for 30 days. If they don't get along with the little Android-powered streamer and gaming console, they can return it without obligation and without being left out of pocket -- so long as they follow the conditions of Amazon's returns policy, which includes keeping the hardware in new condition. Of course, a regular customer could get a similar end result without the invite, by dabbling with the Fire TV for a month and then using the normal returns procedure to get a full refund, but they'd have to pay upfront and possibly also pay for return shipping costs.
Update: We incorrectly linked the 30-day trial with Amazon's standard returns policy, when the former might have some genuine advantages. The post has been changed to reflect that.