As you push the mower forward, gears in the wheels spin these blades. There is another fixed horizontal blade. In Canada I've seen them for sale in Canadian Tire, Revy, Home Depot, and Lee Valley Tools. The argument rages on in the newsgroup, almost every time mowers get discussed, about how much pollution gas or electric mowers produce. Reel mowers don't produce any pollution.
Golf courses use reel mowers.
I think that you'd have to get those blades spinning at a pretty fast RPM before you could risk severing a toe. Just grab it and start pushing. No oil to check, no gas to fill, no cord to plug in. This requires a slight readjustment of how you deal with certain areas of your lawn. The maximum cutting height that a reel mower can be set at is usually lower than the maximum cutting height on power mowers.