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.
Rap to Pop Gender Swap (Becoming a Thug Wife Book 2)
Anything for an A (crossdressing, forced feminization gay erotica) (Teacher's Pet Book 1)
My Nuru Futa Massage (Futanari Massage 4)(futa-on-female erotica)
Hell Week Humiliation and other Femdom Stories
Taken by the Futa Eel (Paranormal Futa Erotica) (Taken by the Paranormal Futa Book 4)
The Paranormal Futas (Futa Erotica Bundle)
Gender Switch Sales Pitch (Quintonal Gender Bender Drugs Book 1)
Tricked and Swapped: Caught Wearing Heels (Gender Transformation)
How To Be A Tranny Slut: Erotic Transgender Adult Fiction