What about sports?
Sports are great. A little common sense goes a long way. We're trying to avoid death and maiming, not bruises. So soccer - yes, jousting - no. And if a participant dies from a rare or freak medical condition I hope their relatives and/or a jury would recognize that as promoter I did everything possible to avoid it (physical exam, etc).
A lot of sports can be organized safely. I lead groups in whitewater canoeing and I take my kids hiking, backpacking, rock climbing, swimming and other activities as well as encourage them to play soccer, volleyball, paintball, laser tag, etc. I find that some activities preceived to be risky, like rock climbing, are not really so. I take my kids' friends rock climbing without asking for a signed waiver because I will make the activity safe for them.
But I would not promote sports where people could be killed or maimed like boxing or race car driving. Just my opinion. And I won't avoid responsibility in the activities I arrange by asking for a waiver.