In a sign of the times, private stock photography company Corbis has decided to give free access to some of its photos for use on websites and in blogs in return for allowing embedded advertising inside each photo. This is yet another move from premium and pay website companies to gain market share, not with more payments from subscribers, but from advertising partners.

Corbis, which was founded almost 20 years ago by Microsoft (NASDAQ: MSFT) co-founder Bill Gates, has never posted an annual profit. The competition has always been fierce and it's only intensified in recent years as free stock photo websites and other photo-sharing websites have made it easier for anyone to use photos on the web for virtually no cost.

Corbis' new website for this initiative, www.picapp.com, will feature photos that can be used by anyone -- but which will contain an ad overlay on part of the image or embedded advertising. On the embedded advertising angle, pop-up advertising will happen when a user hovers over the image with their computer mouse or trackpad. I honestly though pop-ups were an advertising strategy that was almost abandoned by all advertisers due to mounds of negative customer feedback. Guess not.

Even so, Corbis has joined a growing contingent of companies that give away products and services for free on the web in exchange for showcasing advertising to potential customers and buyers. As we all know, Google (NASDAQ: GOOG) pioneered this ad strategy -- and others are recognizing its validity when done correctly.