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.
Humiliating Mr. Smith (Femdom Crossdressing Sissification Erotica)
Sammy the Sissy Cuckold Humiliated and Pleasured By His Wife's Big Black Lovers! (Fifty Shades Pinker Book 8)
Dungeonette: Memoir of a Dominatrix
Gender Swapped The Collection: Combining the Flower Power and My Supernatural Gender Swap Series
Transformed Into a Maid (Transformed #13)
Inked and Bared
Pledging Tau Geta Delta Part 4 - Friendly Benefits: An Erotic Transgender Transformation Adventure
The White Renegade (Viral Airwaves)
Changed & Creamed 3: Filthy Party
THE NEXUS STAFF: A Succubus turned me into a bimbo!