Eberron Campaign Setting

Eberron was the winning entry out of a contest run by Wizards of the Coast. It's a very non-traditional (for D&D) campaign setting with elements of steampunk, film noir, and dramatic flair.

This book presents a richly detailed world; it's obvious a lot of work went in to flesh out the tone and flavour of this relatively newer entry into D&D. Unlike the older settings, the types of adventures that can be had is greatly expanded. By that, I mean that it provides a lot of inherent support for non-traditional adventures. Sure, the Indiana Jones type of adventures are still plenty much available, but it also throws in urban mysteries, political intrigues, and steampunk elements.

You can have player characters playing constructs and shapechangers; psionics are built into the history of the world. A new class that exists to offer the flavour of a world with a higher level of technology advances. It's a fractured world that recently came out of a decades long war, with nations destroyed and new nations born (including monstrous nations). You have militaristic nations, a democracy, a magocracy, a theocracy, and more, traditional and non-traditional. Religion and alignment is much more fluid and unpredictable. So are the common races and exotic monsters, whose traditional roles are often turned upside down, bringing new flavour to them.

In short, it's a new world where traditional dungeon crawls can easily fit in, but at the same time, it provides rich history and lore with which to mesh them together with adventures of the non-combat variety. It has just enough of about a lot of different elements built-in that it can handle just about any sort of fantasy adventure you could throw at it.

(But... I still have a soft spot for the Forgotten Realms)