Amazon has implemented its Look Inside functionality for Kindle books. That means when you look at the product page for, say, The Sixth Discipline, you can read the beginning of the book without needing to download the sample. The same is true for No Safe Haven, of course.
I'm sure it's no accident that this feature was added just as Amazon launched its Cloud Reader function. It helps considerably in overcoming the lack of a buy button in the Kindle for iPad app. If you're using an iPad, you can get to Amazon with a browser, use Look Inside to see if you want the book, buy it, and then start reading it. In fact, since the Look Inside chunk appears to match the free sample chunk exactly (except that it has no cover), you could say Look Inside for Kindle books is really just Cloud Reader for the Free Sample.