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.
Too Hot To Handle (Gender Swap Bareback Fireman Transformation Erotica)
AMAZONIA PART 1: All Hail The Queen!: BDSM, Breeding, Cuck, Menage, Spicy Vanilla (Belladonna Amazonia Erotica)
Holy Switch! (Gender Swap Bareback Transformation Erotica)
Swapped By Their Masters: Victorian Historical Gender Swap Erotica
Punished by Gender Swap (Lisa Feminizes and Humiliates her Boss Book 1)
Ed & Tracey: A crossdressing romance
Seeds of Change
The Changing Room: A Gender Swap Tale
Crossing (Open Door Love Story Book 1)
fuTA 2: Experimental Threesome (Futa on Female Menage)
Futanari Planet 2: Discovery
Futanari Sorority Adventures: Volume 1-5
Love sex and the whip: Training James, the story of a female led marriage
The Metamorphosis of Michael F: A transsexual odyssey of love, revenge and murder