Photo stock (aka
stock photography) is a two-edged sword.
In the short run it's great for designers, art directors and other consumers of imagery. Tons of beautiful, compelling photographs on almost every conceivable subject at your fingertips. (Corel's is of the lowest quality, though. Try FPG, Photodisc, Image Bank or Stock Market first.)
But it's bad news for photographers. In fact, both my friends who are professional photographers consider the explosion of stock to be the death of freelance photography. Before stock, people who needed images would hire photographers to take pictures of what they wanted. Now they just buy a CD or go to a website. For an independent photographer, that increasingly means that either you sell your work as fine art, or you sell to a stock agency, or you have a long row to hoe.
Good luck with fine art as a living. And to sell to a stock agency you need to produce dozens if not hundreds of new images every month. As with every other endeavor that the Internet has converted from a local market to a global one, now only the very best are in demand. The Joel Meyerowitzes and Anne Geddes do very well indeed but the pool gets smaller, and a great deal of talent never gets a chance to get noticed.
In the long run, that's as bad for the consumers of imagery as it is for the producers.