Another cached US Kindle giveaway: 10 copies of DREAMSNAKE by Vonda N. McIntyre. This is my favorite book of hers, which is unlikely to surprise anyone who knows even a little about me. It's set in a somewhat distant future, Earth is not doing well, everyone is poor, and the protagonist is a wandering doctor. The title creature is an alien, and there are genetically-engineered snakes, and biofeedback-based birth control, and so forth.