+1
Someone once said that the next Joker would have to be someone who could match the intensity of Batman onscreen, and I quite agree. That said, it's a shame Willem Dafoe has already played a comic book villain. He would have made an intense, extremely crazy, caged-lion kinda Joker, and that's what I want to see.
Crispin Glover and Adrien Brody are excellent choices, and someone said Sam Rockwell, which I can really picture, too. In keeping with the vain of Batman Begins, the Joker needs to be believable - flamboyant, but not over the top - a more serial killer type.