Game creators can override the number of armies that each bonus gives for their game.
When creating a game, game creators can select the Army Settings tab to see a list of all of the bonuses in the map they've selected. Here they can change the number of armies that each bonus is worth.
Players joining games can see which bonuses have been overridden by looking at the settings panel for the game.
 Zero Bonuses
Some map creators will leave bonuses worth 0 armies in their map. Normally a zero-army bonus is meaningless, but the presence of the zero-army bonus allows game creators to enable that bonus for their game by overriding the value.
The most notable example of this occurs in the Earth map. Hawaii, Korea, Alaska and Japan are each individually a bonus worth 0 armies. Game creators can make these worth armies by overriding them.
 Negative Bonuses
Game creators can also specify that a bonus be worth negative armies. Players who control the bonus will see their income reduced, so it's advisable to avoid capturing the bonus in the first place.