Every so often (okay, almost daily), I run across a product that makes me wish I had a kid. Recently, I saw an ad for the K'NEX Corkscrew Canyon
According to its website, I could "[b]uild a real-working tube park that’s over 3 feet high! The K’NEX CORKSCREW CANYON™ building set includes rod and connector pieces to create a downhill tube park complete with motorized chain lift, a funnel chute and thrill park sounds & screams." Yay!
I am, however, horribly disappointed that no real water is actually used. I'd totally plug all the holes and install a pump.