Amazon regularly gives rewards that can be claimed by skill developers when they publish a skill.
For US skill developers June will be a very special month. Thins months reward is actually an Echo Dot. This is an absolute amazing reward and is a great opportunity for developers that do not have an Echo yet. Apart from the skill being published between the 1st of June and the 30th of June, there are no limitations upon what the skill does.
For the UK, German and Indian skill developers you can grab yourself a t-shirt.
As usual, there is a limit upon how many are given out (2,500 in the case of the Echo Dot, unsure about the t-shirts) but to grab your reward or to look for more information check out the info page.