There are so many free ebooks out there that you could read a book a week and never put your hand in your pocket (or your Paypal). Authors are told it's accepted marketing to offer one book free "so that people get to read you and buy your other books".
I'm not so sure. I don't see J. K. Rowling, Stephenie Meyer and other big names giving their work away for free. Part of me suspects that companies like Amazon say this so that they get to sell their ereaders on the basis that you pay for a piece of hardware and get thousands of new books free. I really wonder how many people stop buying books once they have Nooks and Kindles because there are so many free books out there.
But I'm not totally certain so I do offer one free book. I wrote Sold! A Romance In The Sudan in order to practice writing a long sex scene. I got most of the arguments from friends (Malaysian Indian, South African and Nigerian) on their troubles trying to date across cultural gaps.
can see here!)
I suspect lots of authors do this, which means the free books are only a taste of what their true storytelling is like. Me, I don't rely on free books. I always read the first few pages (20% free) and then decide if I want to buy. That's how I choose print books too.
I'd be interested to do a study to see if readers go on from free books to buy books. If you ever hear of one, please leave a note!