There are quite a few porn directories there with their own transgender erotica categories, but few of them are any good. Most of them serve as search engine bait serving irrelevant ads.
Of all the directories I have linked to, only one remain: the one to Weird & Sexy.
I admit it is a chaotic site, and some sites listed are of a low quality, or even intelligible (as I do not read Japanese).
That being said, I have found several gems in their collections, and their transgender section is huge.
No wonder, really, as it includes everything from trangender fantasies like the ones you find here to shemales and futanari. They include blogs, porn sites, Yahoo! Groups and YouTube videos.
The good thing is that they are now switching over to a new format, and the new site is much easier to navigate.
Click here for the transgender category under the new site.
Here's a video found via a link on Weird & Sexy to metamorphosisrayne's collection over at YouTube (video by Urisei Yatsura).