Manning is making all the right moves in publishing at the moment. Not only can you buy books in digital editions free of DRM, they're also letting you in on each chapter as it's being written with the Manning's Early Access Program.
For $20, I just bought the right to see JUnit in Action by Vincent Massol and Ted Husted (who also co-wrote the excellent Struts in Action) come into existence. The first five chapters are already available and new ones trickle in every or every other week. When it's all done, my initial $20 of course also covers the final digital master.
Once again, when are you going to catch up, Tim? Manning doesn't have to expand their repertoire much to become my new favorite technical publisher.
Now if only Husted and Massol could speed up and get chapter 7 on MockObjects online...