To date the gnarliest one I've ever seen in person was in NY at Holiday Valley. This kid Sam that worked in the cafeteria and was hell bent on being a pro freeskier was always chucking his meat. This kid had more balls than brains and freeskiing was still in its infancy so he could have made it.
Back then they had one jump up top, pipe down the middle, then a second jump at the bottom on Foxfire. Kid points the head wall pumps the first jump, pumps two times on the wall of the pipe, goes straight into the jump and proceeds to do the running man in the air. He sent a 45 foot jump at least 85 feet screaming the whole way. From the chair lift which was a good 500 feet away I watched him sail through the air flapping every appendage and impact right into the ground leaving a 10 foot crater. At the impact there was a loud snapping and then screaming like no man should have ever heard. He snapped both femurs, shattered his right hip, broke both tibia's and fibulas, shattered his left ankle, broke a couple ribs, snapped his wrist, got a concussion, lacerated kidney, and a slew of other things.
He was flight for lifed out of the resort which if you've ever seen one or been on one is not fun. Kids got more metal in him than the Terminator now and walks all disjointed. I just remember that blood curdling scream he made you could hear it over the bull wheel of the chair lift and the rumble of the snow guns.
There is nothing worse than realizing you're fucked mid-air. It's a pretty awful feeling filled with dread of the upcoming impact. I can't imagine how long that 85 foot flight must have lasted in his mind.