The Dark Knight - Comments

You should. Aaaand (I can't believe I forgot this one) Batman: The Man Who Laughs. It's an newer one - and a one-shot - but is also good.

thanks :) i'll check them out

You should read the comics! Read the ones before the CCA kicked in and after they stopped listening to it. So that's about 1950 - 1973. Those just aren't as dark nor fun. At least I think. They changed the Joker during those years and removed him for a while...So if you want to see the real Joker - like the one in the movie - read the ones that weren't following the CCA.
Batman: #1, #251, #321
Joker: #3.
Of course those are just some I like. There's a whole Greatest Stories Ever Told for the Joker and other good stories that aren't in there, too.