Does the Batman Anime count, the one that was meant to fit between Begins and the Dark Knight?
If so I think they already did their version of Killer Croc, and if I'm not mistaken he was a deformed guy who lived in the sewers and was like a supposed myth.
Does the Anime count as part of Nolan's Batman?
Also I had an idea for Harley,
even though I don't think they will ever use her and probably shouldn't,
here it is:
Dr. Harley Quinnzel is a criminal profiler. Her job is to profile and monitor the worst criminals in order for the police to anticipate their actions. (thats what criminal profilers do right?)
Perhaps she is called in when the Joker escapes, She spends night and day studieng his case, his murders, his profile, his life, practically living with him. She spends so much time on his case that she becomes a little too attached, speaking of him with admeriation and deep respect. She begins to slip even further, until she decides to go out into the streets of Gothem to finish what Mr. J started.
Anyway, thats just an idea. I got it from watching the last episode of Psych.

