Yep, I let my kids jump on trampolines, build bike ramps, own go-carts, climb trees, jump off the railroad bridges into the river, longboard down extensive hills, and do all sorts of crazy and risky things. Supervision and explanation of the safety rules (including equipment like safety nets and bike helmets, etc) is key most of the time. The only time my son has been seriously hurt is 1)when riding his bike, hit a rock, and went over the front losing both front teeth at age 6

, 2) somehow falling during recess on the monkeybars requiring 15 stitches to his chin at age 7

, 3)bit by a snake during swimming lessons with the YMCA at a local pond at age 9

, 4) breaking his thumb during basketball practice at school at age 13

, 5) breaking his shoulder playing his first varsity football game at age 15

-- my point, every time my son has been injured, with the exception of the bike incident, he was at a school or camp sponsored event -- and he spends nearly all of his time outside of these events being very active doing some crazy things
My DD10 on the other hand is not very active and it's kinda hard to get hurt playing with your dolls or doing oil paints so for the moment no broken bones and no stitches and I don't really see this in her near future