Shaman Prestige Class ?

[Aitch Eye]

Bombshell Studios has a shaman core class by Chris Jones, author of The Book of Taverns from Necromancer, co-author of The Slayer's Guide to Yuan-Ti, and contributor to several other books. It's a free download, and there's a lot of other nice free stuff (monsters, places of interest, etc.) there as well.

http://bombshellstudios.com/d20/