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.
Walk a Mile
Transgirl Rhapsody: Erotic Transgender Adult Fiction
Bad Lil' Brandy, Busted ~ A Futa on Female Erotica
Futanari Manor (First Time Futanari Erotica)
My Futa Job Interview (Futanari Massage 2)(futa-on-female menage erotica)
Futanari Sorority Adventures Volume 3: Futanari Sorority Does Vegas
From Submissive Wife to Femdom MILF Hotwife: Fat doormat Mary gets revenge on her husband by becoming a sexy femdom MILF slut
Pumping His Meat (taboo forbidden)