I did not know that about Aaron Eckhart. I thought his hair looked great in The Dark Knight though.
Kutcher is my favorite celeb hair transplant case. He did it so damn early that nobody except the hair loss community has ever, or will ever pick up on it. He was a thick thick NW2/2.5 and could still pull off bangs very easily. If you notice though, like the pic Shadow posted, his hair looked a little sparse when it was cut short. And when he grew it long he usually resorted to swooping the bangs over to cover up his temples.
But now his bangs are incredibly thick and it's obvious his hairline has been filled in to a NW1. I'm quite jealous, actually.