Badge of Justice

Badges of Justice, frequently also called Heroic tokens, are a reward which drops from boss kills in Burning Crusade heroic and raid instances. They can be spent at special vendors to buy quality gear.

Source
In heroic mode dungeons, all bosses drop one badge of justice each. In raid instances, all bosses usually drop two, the first boss of a raid instance may drop only one and the end boss in some cases drops three. When a boss drops badges, every member of the party can loot them.

Beyond boss drops, badges can be obtained as quest reward. The Burning Crusade daily heroic quests are the most notable example, the Shattered Sun Supplies may contain a badge as well, and a few other quests (particularly into Zul'Aman) also have badges of justice as quest reward.

Spending
There are several vendors who offer equipment for Badges of Justice. The badges in fact resemble a Blizzard-implemented DKP system. The gear selection offers a complete set of items for group PvE for all classes and builds, ranging from Kara-level quality up to items surpassing even Black Temple drops (still characters only equipped in heroic gear are good enough to enter MH/BT, not more).

The badges of justice can be spent at the following special vendors: See Badge of Justice rewards for a complete list of rewards.

Badges by instance
The following is a list of instances that have bosses which drop one or more Badge of Justice. The best place to farm badges is Karazhan, and the fastest method to get them with a group of five is the Mechanar. The number of badges received assumes a full clear of each instance, the only exceptions being Mana-Tombs which requires a player with the item Eye of Haramad or Shaffar's Stasis Chamber Key to summon in order to receive the fourth badge, Sethekk Halls which requires a druid with the ability to summon  in order to receive the third badge, and Shattered Halls which gives a fifth badge if you kill the  before he kills any prisoners.