those are all pretty bad. but i would have to say the worst i've ever seen was the Cart race a few years ago where Alex Zanardi (sp?) lost his legs when the front half of his car was broken away when he got hit at like 200mph
I wont post it because it makes me sick to my stomach every time i see it
but on a positive note, i read something a few days ago that said he was back racing with prosthetic legs in an F1 car....very inspiring