Google has been steadily lining up deals to distribute its huge collection of scanned digital books, inking agreements with Sony and Barnes & Noble. Now the search giant has found another partner: British company Interead, maker of the Cool-er reader. Google will make more than a million free public domain books available on the Cool-er device and website. Google has been steadily expanding the reach of its book content in a challenge to Amazon.com's Kindle.

The Cool-er reader, which has a six-inch screen and comes various bright colors, has drawn comparisons to the iPod Nano with its size and shape. The U.S. version came out in May and sells for $249 (a bit less than Amazon's cheapest Kindle, the Kindle 2, which has a $299 price tag). Before the Google deal, the Coolerbooks website listed more than 300,000 titles. Interead said about half the million Google public domain books it's adding won't be available outside the U.S. because of copyright issues. Cool-er books come in the open ePub format, which means they can be read on other devices (but not Kindle, which has a proprietary format).

What does all this mean for Amazon? Google is clearly a force to be reckoned with in the small but growing electronic book market. Google's books, scanned from major libraries, tend to be older material, while Amazon puts an emphasis on new releases and best-sellers. But Google's hookup with various Amazon rivals has allowed those companies to vastly expand the number of books available on their websites and devices. And Google has also suggested it may allow publishers to sell new release digital books -- Kindle's bread and butter -- through its search engine.

In a sign of how seriously Amazon takes the Google threat, the online retailer has taken an increasingly public stand against Google's proposed book settlement with author and publisher groups, which underpins the book scanning project.

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