The "fair use" rules for using pictures or quoting text on websites

Since it's easy to take pictures off one website and put them on your own, there's plenty of issues of when it's "fair use" and when it's a copyright violation. Here's a discussion by another blogger:

Patterico’s Pontifications » AP Threatens Blogger for Unauthorized Reproduction of Photos . . . Then Reproduces Photos Withou...

Brian Ledbetter republishes AP photos to criticize the AP, without making money, and he gets threatened with a copyright lawsuit.

Meanwhile, Ashley Alexandra Dupre has equally copyrighted photos of herself on her website — photos that no doubt would have netted her considerable cash had she been paid for reproduction rights — and those photos are taken and reproduced without permission by (among many others) . . . the AP. Which (unlike Ledbetter) no doubt made significant money from the photos’ redistribution, as they were clearly in high demand.