So I've noticed where it lists text-to-speech, lending etc.., there's now an X-Ray option. What does that mean?

Could it be the option to have white text on a black page?

There's info Here.

With a single tap, readers can see all the passages across a book that mention ideas, fictional characters, historical figures, places or topics that interest them, as well as more detailed descriptions from Wikipedia and Shelfari, Amazon’s community-powered encyclopedia for book lovers.

Sounds good for research, but not something I'd do much.

X-Ray: This is a new feature exclusive to the Kindle Touch that analyzes the "bones of the book." It shows passages across a book that mention common ideas, characters, historical figures, and specific places or topics. And then offers descriptions about them from Wikipedia and Shelfari.

http://www.the-ebook-reader.com/kindle-touch.html#

There is a good screen shot at that link of what it looks like. I would love to have that. It's not available for all books, and of course, not for side loaded books.

Not a feature I would use a lot. Drain the battery quicker being hooked in to make use of the reference data bases it would query.  One would hope you could turn it off.  

-RD

It doesn't work that way. It downloads to your device with your book. It's already there, doesn't require a connection to Amazon, and doesn't use any more battery than other reading uses.

What it does, is fill up more of your device's internal memory.  When they say it can hold 3,000 books, that is a little misleading, when for every Amazon book there are additional files d/l not just the book. Maybe that is the case for side loaded books as well. If you look in your "My Kindle Content" folder on your computer (if you have the kindle for PC app) you will notice not only the book file, but corresponding apnx and other extension files. The xray feature generates yet another file for each book that has it available.

I would use it, I think, especially for really long books. I would love to have it, but I don't have a Kindle Touch. Yet.