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.
A Secret Night (My Crossdressing Gay Surprise)
Samantha's Tale : The Deal : Forced Feminization, Bondage, BDSM & Male Chastity. (BDSM & Femdom : Chastity, Bondage, Female Domination & Forced Feminization)
D-Nine Vol.1 (Volume 1: #001 to #003)
Tamara's Tranny Surprise for Tim (Shemale Sex Stories)
Beach Weekend: An Explicit Story of Sexual Discovery