9. Paying For Harley's Uni Tuition
Batman Confidential is a funny old comic, shown nowhere better than when Joker initially meets Harley Quinn while she works in a bar, and pays off her entire university fees after they've had approximately one conversation.
It's not saving the world or anyone's life, sure - but the fact that it isn't a grand gesture means all the more, as it shows the Joker is capable of gestures of kindness that extend beyond making sure he can still fight the Batman.
On a practical level, it's also a pretty solid sign that the twisted clown has some capacity for compassion left in him, as he recognises that Harley went out of her way to be kind to him, and tries to do a good deed for her in return.
Also, American university tuition can cost up to $240,000, which certainly would make you feel like whoever paid it off for you was a legitimate hero.