I do not think that writers should give away their work for free to magazines, newspapers or web sites. In fact, too many writers make a practice of that, dragging down rates for all of us.
Books, however, seem a different story. In a Yahoo! news story, Scott Sigler talked about how he built a fan base by giving away free copies of his book. That seems counterintuitive, but it worked for him.
The strategy of giving away some of your work as a marketing tool does, I suspect, work for a growing number of freelancers.
“If they try you out for free, they become lifelong customers. There are so many affordable ways to go find people. For readers, they are respected as intelligent consumers,” Sigler said.
He gave away copies of his first book, got a contract with Crown Publishers, and then gave away more copies of his book: it had been so effective a marketing tool, he kept going. In this slide show, he talks about the idea of creating a free trailer to lure people in.
I think the lesson here is that book buyers, once they’re hooked, will pay for convenience and format. If they like your style, they’ll pay for the convenience of having it in the format they want: a book.