Kris Rusch has a new The Business Rusch chapter up on setting e-books temporarily free as promotion. This chapter was sparked by the kerfuffle over James Crawford's Kindle book mistakenly (it seems) being set to free on Amazon because an excerpt of a few chapters with (it seems) the same title was being given away for free over on the B&N Nook site.
Kris talks about what happened and how it was reported (and has some fairly harsh criticism for the reportage about the incident), but of even more interest, she tells about what happened when one of her own novels was recently set to free for a while by the publisher without her knowledge. Mr. Crawford is incensed at the results of his unwillingly free book, but Kris is delighted with hers. She discusses what the difference was, and why the give-away worked so well for her and so badly for Mr. Crawford. The mechanisms and strategies she discusses are very useable by self-pub writers who have the freedom to mess with their own prices as they choose. Check it out.