Just use coupon code LN49C at Smashwords to get your free copy.
This coupon is only good through Tuesday, September 18, so hurry to get your copy.
And please feel free to share this coupon on your blog, Facebook, Twitter, etc.
Edited to Add: I just uploaded a new edition of my book to Smashwords. The only change was in the formatting, so hopefully it will take care of the Table of Contents error in the .epub format.
The (hopefully) corrected edition will have “Second Smashwords Edition / September 2012″ on the title page.
If you have an earlier copy and the messed up TOC bothers you, you can download the new edition for free from the link above.