loads ;
worst is going over a jump and losing control of bars for landing, ouch, so that's skin ripped off my hand so could see muscle.
Next ; shopping bag caught in my front wheel, I went over bars, concussion and night in hospital.
More recently 2 weeks ago, I was trying manuals and tore my right shoulder muscle, 2 weeks of agony and off all sport pretty much.
2 years ago we set a jump over my mates pond, I did it in the dark, hit the farside, and over the bars, landing on a rock, lot of facial grazing and torn left shoulder muscle - hospital visit...again, my mate did the same jump, nearly 1 year to the day = he ended up with a spiral fracture in his left calf, so plaster & crutches for 6 months, pins in his bone for 1 year.
He's 30 and will never do any tricks of any sort ever again, except windsurfing, loved snowboarding, I decided though, I'm same age as him @ 30 years old, to get right on it and do as much as I can as you never know what will happen in the future etc.
keep riding
* safely where possible.