I really, REALLY like this take on it. I've only seen the version in Batman The Animated Series, where it was more like a tragic struggle that Harvey eventually lost.

This version shows how a mostly good man can slowly descend into corruption without even realizing it, to the point that the acid attack is only the final nudge he needs rather than a dramatic change. And hell, even if you hate his methods, you can even sympathise with him - I can't be he only person so sick of the Joker Immortality that I wish that someone just kill him already. But this strip even shows the flaws of the typical 'the Joker should be one exception' line of reasoning; once you start that slide towards corruption, it's very, very hard to go back up. And then it really might take only one small thing to push off the edge completely ...