I don't know how long it will last, but Chris Anderson's
FREE: The Future of a Radical Price is free once again on Kindle, plus the offer to get Anderson's earlier book,
The Long Tail, (Revised and Updated) for free is still valid as well. So, for zero cost you can get both books, with one order.
If you already purchased
FREE earlier, then you'll need to call Kindle support and return that copy of the book and re-purchase it. I sat with my finger on the one-click button and grabbed it as soon as the representative said the first order had been returned. Both titles are now safely ensconced on my DX, waiting for me to find time to read them. If only these free titles came with more free time to read them....
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If you don't have a Kindle or iPhone, the best deal I've found that is still current on this title is from Fictionwise.com - this week the title is part of their 100% micropay rebate specials.