The following method is based on Bruce Cost's Ginger East to West, a cookbook I picked up on a remainder table in Singapore and really love--it's written homeschool-style, with a lot of history tucked in between the recipes.
As usual, though, I didn't preview the recipe so did not adhere to the amounts he suggested, or even to the ingredients (he suggests Chinese yellow rock sugar). It still worked. :)
1 large piece of the freshest, youngest ginger available--look for light-colored, smooth skin
1-2 cups sugar
Soak the ginger in cold water overnight. In the morning, drain, cover with more water, bring to a boil, and simmer. Drain and let cool.
At this point the skin will practically slide off, but a sharp paring knife helps. Cut the peeled ginger into pieces. Cost suggests 1/8" slices or the historically-accurate "lacquered chopstick" width. I cut my pieces into rough little cubes, because that's how I like it.
Simmer these pieces in water for 10 minutes; drain and repeat the process. Drain again.
Bring to a boil once again and simmer, this time watching and stirring as the syrup thickens, then crystallizes. It took a bit over an hour. First, it looked like this:
I had been concerned about the fact that my ginger-to-sugar ratio was different from Cost's, but I guess there is a saturation point and the rest of the sugar is yours to sift off and use in making gingerbread men or something equally delicious.
If your ginger is stickier than mine, you can dry it on waxed paper or toss it in extra sugar. I didn't need to do this, so put it straight into a candy dish.