Surprise Hits: Kindle's amazing sales numbers don't go unnoticed

In November 2007, when Amazon (AMZN) unveiled its e-reading device, the Kindle, I wrote a column predicting that it would fail to find traction, given its cost ($399) and the cost of downloaded books (around $10 per).

Boy, was my crystal ball cracked. A Citigroup analyst estimates that Amazon sold half a million Kindles last year (and could have sold many more, had it not run out during the Christmas season). The introduction of two extensions this year -- the improved Kindle 2 and the textbook-friendly Kindle DX -- has built on the brand's success.