While a lot of high-quality Stock Photography (such as that used in professional advertisements) requires a fee, the casual user can find a lot of good stock available on websites such as DeviantArt. A multitude of artists there put up their work for you to use, provided you follow their terms of use - and almost all of them are very reasonable. The stock available is huge in variety, and is a godsend for the casual crafter, hobby graphic editor, etc.
I personally put up a lot of stock photographs of flowers and backgrounds - today I added two flower stock packs featuring high-resolution images from Monet's Garden at Giverny, and plants on the big island of Hawai'i.
The majority of stock images available are models, and some of those are incredibly professional and varied - MJRanum-Stock, for example, is a stock-exclusive account from a professional photographer.
Locations are also big - you can find ANYTHING! The below example is one of many photographs I took in France, and have since made available to the general public to use.
So what are you waiting for? Start looking around!