I must admit that "Dark Knight" is now currently my favorite super hero movie that has come out thus far.
I was amazed by that movie.
My mind was blown by the acting.
Let me put it this way:
I'm not sure how well they can do a movie after this one because of how well done this movie was done...
and i think they have run out of good Batman villains- the only other likely villains they would pick are the Riddler and Mr. Zsasz
The other villains are not very realistic (due to that the batman series has been aiming at realism for their characters. Thus, they probably are not going to pick villains who have super powers).
They have tons of villains, but they are either not realistic or they have super powers. For example: Penguin, Cat Woman, Clay-face, Crok, Baine, Mr. Freeze, Ventriloquist and Scarface, Mad-Hatter, Poison Ivy, etc. *i'm too lazy to type all the villains that i can remember*