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.
Transexual Erotica: Volume 2 (Transexual Erotica Compilation Series)
Coming First (The Woman First Chronicles Book 1)
My Girlfriend's Big Instrument (Transgender Erotica Romance Book 1)
Massaging the Married MILF (Futa Massage Service 1)(Futa-on-Female,Cuckolding, Older Woman/Younger Futa Erotica)
Submitting to Lisa: Part 1
Encounter Of The Weird Kind
Shemale Temp-tations (First Time Shemale Erotica)
Tess Turned Her Husband Into A High Priced Call Girl (Gender Swap Revenge, Feminization Punishment, Transformation Fantasy Book 1)