The Trampoline can be a lot of fun. Craft one, place it on the ground and bounce away. It gives a huge jumpboost when you step on one. Even better is the fact that if you place another one alongside the first, you jump higher. The more trampolines you add, the higher the jump. Try making a 4 x 4 grid trampoline and you'll see what I mean. Oh Yes, and if you are worried - you take no fall damage coming down from great heights. Watch out when breaking a trampoline, 'cause blocks like to jump to, and if as they break, they land on the trampoline, they'll be jumping around like you did.