Techdirt has just posted a summary of their recent efforts to give away ebooks ebooks. Mike Masnick let buyers name the price for any of the 5 titles, and he failed pretty badly at giving them away. Even though over half of downloaders paid nothing, the mean ebook price was about
Update: I was looking at the wrong figure when I originally wrote this post. The average of $4.95 only reflects the paying customers, not the freeloaders.
Joking aside, the reason i think this sales effort succeeded where other freebie efforts failed is the design of the sales page. The pricing options default on $5 (the most commonly paid price), and anyone who wanted to get the ebook for free had to make a conscious effort to do so by selecting the last option and typing in zero.
This differs from a lot of other free ebook experiments, in particular the ones many authors have attempted on their own websites, because it defaulted to a payment option, not the free option. Furthermore, the ebookstore drew its customers from Techdirt's readership and fanbase, people who already liked the site and wanted to reward it.
I know of several authors who offered one or more free titles and put out a tip jar (donations through Paypal, for example). This does not work very well for much the same reason that my donation button down near the bottom of the page does not generate much income. Both default to unpaid instead of paid.
Free content can work; you just have to be careful how you offer it.