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.
Oh My! I'm a Woman!: Gender Bender Bundle
One Week Part Two
Stuffed by the Futa: Make Him Watch (Futa on Female, Cuckold)
Prodded and Probed (A Futa Medical Exam Menage): Book 1
A Week in the Woods with Family: Ramblings of an Author in Cottage Country
Fanny's Futa Makeup Mirror (Semper Futanari Book 2)
Shipwrecked on the Island of the She-Gods: DAY ONE (A South Pacific Trans Sex Adventure)