…turns out to be quite considerable. A glacier-slow drip of sales at Amazon became a torrent of downloads when the book was made free instead of 99 cents/70 pence.

Downloads at the UK Amazon site passed the 1,000 mark this morning, while over at the US site, the figure is close to 3,000.

It really brings home the scale of Amazon’s market share. The book has been freely available online since late 2009, via Scribd, Smashwords (and the various sites to which Smashwords ships books), Feedbooks and Manybooks. It took eight months to reach 4,000 downloads on Smashwords, while on Amazon that number has been reached in less than two weeks. It’s exciting, but a little bit frightening, too.