Last year Sharon Lee and Steve Miller tried an experiment of writing a draft of a new book set in their Liaden Universe online. The put a new chapter up each week with some weeks missed for various reasons. I really enjoyed reading it and when Baen published all their earlier Liaden books as ebooks I bought them.
This first draft was called Fledgling and is still available online.
This year they have decided to continue the project with the draft of the next story about the same character, and the first three chapters are already up. The new story is called Saltation.
The project relies on donations to support the writing of the draft, so if you enjoy it, donate!