Currently wearing a pretty badass Joker shirt...couldn't find a pic online, but it's this image:
...only instead of the actual picture, it's grafitti style and is designed entirely out of "HaHaHa", except for the mouth which is made of of Joker quotes. It's hard to describe I guess, but I love it. Guess it's similar in style to the final Dark Knight poster, the one made out of cards? Kind of in that vein.
That Eraserhead shirt is fantastic, by the way.