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.
Punished by My Futa Boss (Futa on Male)
Mother's Secret Sissy Son (Mother's Secret... Book 2)
FutAir: Flight 2 (A Futa on Female Menage Erotica): Episode 2
Sentenced to Gender Swap: College Kid Discipline
Sentenced to Gender Swap: Gay Game Gone Straight
Male to Female Gender Bender Bundle: Volume 1
Transformed Into a Cougar (Transformed #10)
Teaching Hana - A Transgender Fantasy