Amazon (NSDQ: AMZN) isn’t yet at the point where investors are demanding returns—or even hard data—on its digital initiatives. The company’s core e-commerce business has performed so well that it’s largely gotten a pass in these areas. Eventually though, it could find itself in Netflix’s situation, making significant digital investments that crimp the bottom line, with a very hazy outlook on when or if that money will breed and come back home.

WSJ offers an overview of what the company’s done so far with an estimate of $300 million invested into digital media over the last three years. That money, spent on such projects as Unbox, the Kindle and the MP3 store, isn’t overly burdensome, considering that the company had over $1 billion in cash flow in 2007. But revenue for all of these things is estimated at just $100 million, and it’s likely that Amazon will really have to ramp up its digital spending in order to compete. Eventually, the company will have to say more than that it’s “very happy” with its initiatives, which is what a spokesperson told WSJ.

Meanwhile, Amazon reports this evening. Analysts are expecting around $4.1 billion in revenue, for growth of 35 percent. EPS estimates are for $.32 per share, compared to $.26 per share a year ago. Investors will be listening for any clues on the performance of their digital operations, but expect nuts and bolts stuff, like the health of the US consumer, to predominate.