Joker for new Batman movies?

I honestly can't see another man ever matching the performance Heath Ledger gave us in the Dark Knight. I was wondering, though, does ayone agree that Lewis Black could have potential with a little work? I might also have thought Johnny Depp would fit the role as he is a great actor but I think I would like to see something a bit more fresh and risky if the Joker should ever re-appear in a future Batman film.