Bukkit

Below is an example of how your questions.txt could look with categories included.
Feel free to copy/paste the below into your own questions.txt to get started!

|General|
Who created Minecraft? | notch
What liquid do you need fire protection to swim through? | lava
TRUE or FALSE.  You're immune to fall damage if you can fly. | true
TRUE or FALSE.  Dinnerbone is a Minecraft developer | true
What mob drops String when killed? | spider
What mob drops Gunpowder when killed? | creeper
What mob drops Gold Nuggets when killed? | zombie pigman
|Farming|
What do you plant to grow wheat? | grass seeds
TRUE or FALSE.  Do you plant Potato seeds to grow Potato crops? | false
TRUE or FALSE.  Do you plant Carrot seeds to grow Carrot crops? | false
What animal do you shear for wool? | sheep
What animal provides milk? | cow
What do you give pigs to breed them? | carrot
What do you give sheep to breed them? | wheat
What do you give cows to breed them? | wheat
What do you give chickens to breed them? | grass seeds
|Geography|
What direction does the minecraft sun rise from? | east
TRUE or FALSE.  Does it rain in Desert biomes? | false
TRUE or FALSE.  Does it rain in Savannah biomes? | false
TRUE or FALSE.  Does it snow in Ice Plains biomes? | true
What direction does the minecraft moon rise from? | east
What spiky plant are you likely to find in the Desert? | cactus
|Ores|
TRUE or FALSE.  Most ores can be combined into ore blocks | true
What ore can power devices? | redstone
What ore is used for enchanting? | lapis lazuli
What ore is used to make torches? | coal
What ore has the best enchanting properties when made into items? | gold
What ore has the best durability when made into items? | diamond