Every Friday I take the initiative to search through thew newly free titles on Amazon, and to identify those that might be of interest to trans* readers, fans, and lovers. Even if you don't have a Kindle, you can still download the titles through one of Amazon's free reading applications, and covert it (if need be) with Calibre. I can tell you I do most of my reading on my iPad, using Kindle for iPad, and it works beautifully.
Please do be sure to check the price before downloading anything, though, as most freebies are limited time offers, and some are specific to certain regions.
Gender Swap - The Cuckold Joins In (Hotwife Humiliation, Sissy Feminization, Interracial Cuckold Book 1)
The English Wife's Slave: A Bdsm, femdom, chastity story
Futa World: Origins: (Futa/Female and Female to Futa transformation)
The Gnoll's Concubine (Serving the Gnoll Book 1)
The Sissy Cop, His Wife and Her Girlfriend: A Femdom Fetish Threesome Story (Rear Eye for the Straight Guy Book 3)
Educating the Boy 1: A Milf/Femdom/Stepmom Erotic Romance
OMG, I've Become a Teenage Girl!
Dancing on the Futa's Pole (Aphrodite's Devils 1)(Futa-on-female, Menage, MC, Exhibitionism Erotica)
Revolution on Highway 73 (Hope's Apocalyptic Adventures Book 1)