
A Fire Upon the Deep
I just re-read this for the third time. So good! Really fun reading. And just chock-full of ideas, there's a whole lot of original sci-fi concepts well elaborated here. I think my favorite may be the Net, the idea of old-school Usenet turned into a galaxy-spanning cultural medium. But also the conceit of the galaxy organization, the zones of thought.. And the pack minds of the Tines, and the terrifying singularity-like Powers, and, and... just a lot of great ideas in this book.
Reading this the third time I really appreciated how well drawn the characters are. So many different ones! And legimately of alien races, with alien modes of thought. I even found the Skroderiders compelling this time, particularly the tragic story of the Rider's Myth. It's good deep sci-fi but it's a remarkably humanistic novel too, with fun characters and exciting plots. What a great novel.
Worth noting there's a version of this book out there with the author's notes while writing them included. I wouldn't recommend reading the book this way, the notes are distracting, but it's interesting to be able to consult them when considering detailed questions.