There are a good number of prestige and alternate/expansion classes available out there for D&D. This thread is for the discussion of them, to help those with a limited understanding of them know more about them and how they work.
For instance, one of the players in the current campaign I'm running has approached me about multiclassing into a Dragon Shaman, a class introduced in the PHB2. He lent me the book, and although I haven't had a chance to read about them much yet, I'm intrigued by the idea, but cautious. Wikipedia has a good article about them, but I'm curious as to experience other players or DMs have had with this particular class. Are they far too powerful? Broken somehow? I'd like to introduce the class carefully, using story events, since it is such a radical departure from his half-orc fighter character as it stands already, but I'm wary about adding something so different from the basic classes I'm used to without a good understanding of it.