The Baltimore Sun had a list of Memorable Sports Injuries and I think we all know which Redskins' moment made the list:
Joe Theismann (1985), Washington Redskins quarterback: Theismann's compound leg fracture, which occurred when he was sacked by the New York Giants' Lawrence Taylor, was remarkable because it was seen live by tens of millions on Monday Night Football and for its gruesomeness displayed in reverse-angle replay. The injury essentially ended Theismann's career.
I encourage you not to watch this video, as it's pretty sick. LT immediately jumps up and signals to the Redskins line, probably because he heard the bone snap. When he puts his hands on his head you know something bad just happened, although you can't see it from the original angle. Fortunately (or unfortunately) MNF provides you with a full view of the injury. If you hadn't seen this video, you've been warned:
Update [2007-4-6 11:44:41 by Skin Patrol]: As Burgundy And Gold pointed out, Hogs Haven should at least give equal time to injuries suffered by other teams, as this is a Redskins Blog. Let me preface by saying that I do not wish injury on anyone. Additionally, to Troy Aikman's enormous credit, it sounds like he's got a pretty good attitude about his concussion.