UnsolvedParadox

100%, without question.

I'll put in another vote for Joker vs Daredevil, especially with what Bendis, Brubaker and Diggle have done with the Man Without Fear. I can see the Clown Prince of Crime fitting in really well with that set of characters, especially Bullseye and Typhoid Mary.

Joseph Gordon-Levitt would be an interesting choice, but he'd have to adhere to Heath Ledger's portrayal pretty closely. 
 
I actually like the idea of The Dark Knight Returns a few years after the 2nd movie, and a slightly older Joker being portrayed by Johnny Depp if Christopher Nolan is set on revisiting the character.

A bit, but that's not what defines Heath Ledger's portrayal of the character (any more than Steve Borden wearing the outfit in WCW and TNA Wrestling).

Joker uses everyone, it's a core part of his personality.

Joker has a sinewy and spastic fighting style, but that unpredictability mixed with his vicious streak and willingness to fight dirty are pretty effective. 
 
I thought The Dark Knight did a great job of capturing that.

What the...huh.

This would be cool! Totally works for me, although the Hugo Weaving suggestion would also fit.

I can't see this happening without being really contrived and forced. Resist, resist!

Penance with Cyclops, that's about it now that Psylocke has been announced as DLC for the 360.