Damage meters in World of Warcraft can be both a blessing and a curse. On one hand, they can give you detailed information about incoming and outgoing damage in order to help you decide on the best gear, the best talents, and the best spell or ability rotations to get the most out of your character. On the other hand, their list format can turn instance groups into a competitive game where the person at the top "wins" -- a dangerous thing when a DPS chart can't tell you anything about threat or deaths, nor utility abilities such as crowd control or dispels. However, I always like having Recount -- not only because it collects a metric ton of data about you and anyone you group with -- but because the information it tracks can help put DPS in the broader perspective.
To the right you see Recount's main window. Right now it only lists two items -- my Rogue alt and the elemental pet of someone I was grouped with before taking this shot -- but in a large group there will be a line item for every group member and pet, showing total damage, DPS, and what percentage of the group's overall damage they've done. If you mouse over anyone on the list, you will see the pop-up to the right, listing the top three attacks, top three attacked, and the damage done to each.
But Recount goes in to much more depth than this. Want to know the wealth of information that awaits you? Keep reading!