They're known for their wooden coasters. They have 3 of the top 50 according to this list (#2, #35, and #44)
http://goldenticketawards.com/top-50-wooden-coasters/
The beauty of Knoebels is that I can park my car for free. Walk into the park... also for free, eat decent food and not overpriced crap. And it's in the woods.