Online giant Google (Nasdaq: GOOG) just reported fourth-quarter results, and investors aren't happy. Shares fell as much as 9.4% in after-hours action on epic trading volume.

What did Big G do to deserve a public spanking like that? Well, analysts had been looking for $10.51 of non-GAAP earnings per share on adjusted sales in the neighborhood of $8.4 billion. All Google could muster was $9.50 per share on revenue of $8.1 billion.

Granted, we're still looking at a 29% year-over-year revenue boost and 8.6% higher earnings per share. On the other hand, operating cash flows jumped 11%. Fools love to see this metric outpacing the accounting construct we call earnings, because cash is a lot harder to fake.

Also, Google never offers financial guidance, so analysts are left to their own devices more than they're used to. But still, that's the Greek chorus that Google must please or else face downgrades and/or angry research notes. These things really do move share prices.

CEO Larry Page doesn't think the quarter was all that bad, of course. "Google had a really strong quarter ending a great year," he said, and Page is also "super excited about the growth of Android, Gmail, and Google+."

Google users clicked on 34% more ads than they did a year ago, though each click generated 8% less revenue. If Google had been able to cut that per-click revenue drop to 4%, the company would have met Street targets. Managing this metric is the key to Google's future profitability.

True to form, management didn't break out results like Android-related revenues or YouTube sales, and I doubt that the earnings call will shine much light on these details. But Page did mention that Google+ more than doubled to 90 million users in just three months. Not too shabby, I say. That project is looking more central to Google's modus operandi every day, so a strong user base is a good sign.

This setback erased the gradual gains of the past three months in one fell swoop. As a Google investor, I'm keeping a somewhat nervous eye on that cost-per-click metric, but by and large I see no reason to dump my shares.

On the other hand, shares are now trading for just 18.7 times trailing earnings. Given that the company sees annualized EPS and cash flow growth around 30% more often than this single-digit anomaly, I think the stock is a steal at these prices. But if you still don't like Big G even at this discount, there are other ways to invest in the tremendously successful Android platform. This free report will show you how.