The talented Red Tash is offering This Brilliant Darkness for free on March 4th only. I've reviewed this book before, and liked it a lot. It's well worth checking out, especially at the price. The link's below. If it's not still the 4th, just buy a copy. It's good stuff.
There are rumours of other giveaways coming up, there is a sequel in the works, and she's written some other stuff, so consider a visit to http://redtash.com/.