I have just started Dirty Streets of Heaven, by Tad Williams. Williams might be best known for some ofhis more epic works, liek the "Memory, Sorrow, and Thorn" series, in which he essentially rewrites the Lord of the Rings for more modern sensibilities.
It is only in Dirty Streets of Heaven, however, that I have learned Williams' range of writing. It is, for lack of a better term, in a completely different "voice" than other work of his that I've read. Still well-written, in general, but is sounds and feels quite different. It is refreshing to see an author stretch into different styles like this.
For the curious - Dirty Streets is basically a noir detective story, but the main character is an angel.