O'Reilly Media publishes DRM-free ebooks. Their slant is toward technical resources such as user guides and technical manuals but they have an interesting mix of other, timely non-fiction.
A few "wow" points: you can download any other format of their ebooks once you've "bought" your copy and future updates/editions are free. O'Reilly seems to "get it" - they're licencing the CONTENT not the container.
I highly recommend one of their books titled "
Open-Government - Collaboration, Transparency, and Participation in Practice" which has multiple authors and should be right up the alley of a lot of folks here.
They even have a "
Kindle Mini Missing Manual" which I bought and am quite pleased with.
Check for coupon codes. The above two books I mentioned, with their online coupon, came to less than Amazon charges.