Who needs Harry Potter? Amazon.com (Nasdaq: AMZN) came through with another monster quarter last night, silencing critics who figured that the company's third-quarter performance had been inflated by sales of Scholastic's (Nasdaq: SCHL) final entry in the Harry Potter series.

Yes, Amazon continues to roll along nicely. Net sales during the holiday quarter soared 42%, to $5.7 billion, well ahead of Wall Street's expectations of a 35% top-line spurt. Profits more than doubled to $0.48 a share, in line with analyst profit targets.

No one is doubting the viability of Amazon's model. The company is now profitable year-round. It closed out the year with $1.2 billion in free cash flow. Since no one is shocked at Amazon's profit-milking prowess, let's focus on what's really been blowing me away over the past two years: accelerating growth.

Amazon.com

Sales Growth (YOY)

Q1 2006

20%

Q2 2006

22%

Q3 2006

24%

Q4 2006

34%

Q1 2007

32%

Q2 2007

35%

Q3 2007

41%

Q4 2007

42%

See the trend? With the exception of the first quarter of 2007, the year-over-year net sales growth rate in each quarter has clocked in faster than the previous quarter. The last time that Amazon was growing this quickly, it was 2000 and Amazon was working off a considerably smaller base.

OK, so maybe the plunging greenback helped prop overseas results higher. If it wasn't for favorable exchange rate translations, net sales for the period would have inched just 37% higher. Still, that's blazing speed when you consider that smaller companies like RedEnvelope (Nasdaq: REDE), Bluefly (Nasdaq: BFLY), Overstock.com (Nasdaq: OSTK), and Drugstore.com (Nasdaq: DSCM) are all growing slower.

The trend is likely to slow in 2008. Amazon is looking for sales to climb just 26% to 33% higher this year. Still, it seemed two years ago as if even those growth rates were lost forever.

Amazon has clawed its way into consumer fancy through its widening collection of offerings, partnering with third-party vendors, and the success of its Prime membership, where active shoppers pay $79 a year for free two-day shipping (and heavily subsidized overnight deliveries).

Did Amazon do enough to excite the market? Not really. Shares dipped after last night's report, even though warts are hard to find beyond a dip in domestic operating margins year over year and overanxious investors upset that the company simply met expectations. Hopes run high when you're a blue chip trading at what is now 66 times trailing earnings.

My advice is to approach continued weakness as a potential entry point. Amazon's guidance has been historically conservative. Yes, last night broke a streak of five straight quarters of exceeding profit expectations, but Amazon continues to humble Wall Street when it comes to net sales.

Amazon's getting bigger with every passing quarter, and I don't see it slamming on the brake pedal anytime soon.

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Longtime Fool contributor Rick Munarriz has been shopping online for about as long as Amazon.com has been in business. He does not own shares in any of the companies in this story. He is part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.