It seems that PS Publishing is periodically offering some ebooks for free on Amazon. Several weeks ago I got The Ghostwriter by Zoran Zivkovic. And before that, it was Osama by Lavie Tidhar.
Today, it is Starship Summer by Eric Brown (whose The Devil's Nebula is one of the books I'm looking forward to in 2012) that is free. The ebook is a story about an alien artifact and comes with a foreword by Peter F. Hamilton.
So, what are you waiting for? Go grab it while it's free!