With every passing year, Amazon pulls out a fresh growth initiative that manages to tack on more revenues to the income statement. Back in the last decade, Amazon's sales grew an impressive $3 to $4 billion annually. More recently, sales shot up $10 billion in 2010 (to $34 billion), $14 billion in 2011, and are projected to grow at a similar pace in both 2012 and 2013. How many other companies can pull off that kind of growth without resorting to acquisitions? Only Apple ( AAPL) and Google ( GOOG) can make a similar claim.

Still, it's far to wonder when Jeff Bezos will start to pay attention to the bottom line as well. Amazon has never earned more than $2.50 a share in any given year in its existence, and that's unlikely to happen in 2012 or 2013 either. At some point, this $250 stock will have to morph into a really impressive profit growth story for shares to scale new heights.

DVita Healthcare

Projected 2013 sales growth: 26%

This is fast-becoming one of Warren Buffet's favorite stocks. His investment firm, Berkshire Hathaway ( BRK), has been acquiring roughly one million shares a month and speculation has risen that Berkshire might eventually expand its current 13% stake to 100%.

You can understand the appeal. This operator of 1,900 dialysis clinics is a steady grower that throws off ample cash. Free cash flow has steadily risen from $300 million in 2008 to roughly $780 million in 2011, and should exceed $1 billion by 2013.

Still, investors need to be aware of the cost pressures on healthcare as they assess an investment in DaVita ( DVA).

The company currently bills Medicare and Medicaid an average of $88,000 per patient, and the total national tab now exceeds $30 billion. You can be sure the government will seek to drum some savings out of Medicare and Medicaid as the Federal budget tightens, and Davita will have to lobby hard to be sure that it's reimbursement rates don't get trimmed.

To see these stocks in action, visit the 5 S&P 500 stocks poised for stellar sales growth in 2013 portfolio.

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