As the title says, every attendee of C++ on Sea will get a free copy of Nico' Josuttis' eBook, "C++17 - The Complete Guide"!
by C++ on Sea
About the article:
We can now announce a special deal we've arranged with Nico which means we'll be giving every attendee of the conference a coupon code to obtain a free copy of the book in electronic form (current suggested price: 37.90 USD). You'll have immediate access, and continue to get updates as the book progresses to completion.