Slowing down a fan motor?

My dad replaced the fan motor in my bathroom, and I claimed the fan motor! What I want to do is either turn it around (so the fan spins and chargers the battery, not battery drains, and fan spins) or slow the fan down as to use it in a model of a farris wheel. I would love to do the ferris wheel idea, but like I said, no idea on how to slow it down! I know about using a light dimmer, but I don't want to use it unless I need to....