Tor's Kindle books are also DRM free, although IIRC the process of exporting the DRM free files outside the Kindle app is somewhat non-intuitive.

Thanks to lawyer back and forth Amazon now has an explicit note on Tor (and Baen and a few other similar publisher titles) making it clear that the file is DRM free at publisher request. It seems like funny language in Amazon's store pages because it sounds like they are treating it like a book defect the way it is written, but the bonus is that you can look for that "warning"/"acknowledgment" when you want that best of both worlds situation where you want to get Kindle features on a book but support a DRM-free publisher over alternatives.