I have to throw A Darkling Sea into the mix.
This book takes a very interesting spin on something that I have put a great deal of thought into over the years. To what degree does the type of sensory input we are able to perceive determine the limits of our thought and imagination? What other methods of doing things would we be capable of with slightly different sensory apparatus? How does a completely blind race that lives underwater write things down? How do beings that communicate through olfactory signals keep secrets from each other? What effect do these evolutionary quirks mean for the development of a culture, a civilization?