1. "The Da Vinci Code" by Dan Brown is being made available as a free ebook this week, as a publicity stunt for his upcoming new book. Here is the Amazon link, the Nook link and the Google Books link.
2. "All Things Are Lights" by Robert Shea is perhaps my favorite historical novel (it's set in the Middle Ages, during the time of the Crusades) and it is available free under the Creative Commons license; download links are here.
3. Here is a list of books released as free ebooks under the Creative Commons license. I enjoyed two of these books, "Little Brother" by Cory Doctorow and "Free Culture" by Lawrence Lessig.