Yo, authors! I was kidding about El Dorado. This is much better hidden.
There's something provided by Amazon. It's free, it's useful, and it's very well hidden if you don't have its exact coordinates. It's Amazon Author Central.
(See, I cheated. I gave you the direct links.)
It seems to be conceived as a hybrid of the very familiar Kindle Direct Bookshelf, where you can track sales, etc., and a personal profile page for you, the author, as well as a spot to track customer reviews.
Whether it will eventually expand to other Amazon country sites, maybe supplant the Bookshelf altogether, possibly not even Amazon knows.
However, as anyone who's spent a few minutes wandering around the books section of Amazon scoping out the competition knows, there's customer reviews, luvverly little boosts that they are, and then some people have an entirely different section, called Editorial Reviews.
This is one of the fun things that it seems you can only access from Author Central. Essentially, Amazon doesn't allow professional book reviewing sites to publish reviews to your book site. However, you are allowed and encouraged to take your pro review and copy it into your Editorial Reviews area.
From there, you click on the book you want to add an editorial review to, and go into the Editorial Reviews tab below the book image. You can add (a) review(s) there, as well as product descriptions, some about the author blurb, and a number of other tidbits. All good cess to get people to stop and buy your genius.
Your Author Page is another nice extra that comes to those who persist. You can add a photo, a bio, your Twitter feed, your blog and quite a lot of other stuff.
Have fun - love and wiggles, the Indie Publishing Hacker.