Baseline DPS comparator tool
 

Collects DPS data from all users under standardized conditions (self buffs only, no flasks/pots/food/etc, single-target, fixed duration DPS) and allows the user to compare their DPS with others of the same spec and approximate ilevel.

So anyone could find a lone target dummy and start attacking it. If they meet the standard conditions outlined above (and would be specified in the addon) then the DPS data is collected and then shows the user how they did compared to people of the same spec in say, a ±5 ilevels range of their own (or whatever range the user selects). If anyone tries to cheese or inflate their test by say, using a potion, getting additional raid buffs, or hitting multiple targets their data is disqualified. A "Check Validity" button could tell the user if they have any buffs they need to click off in order to meet the criteria, as well as afterward saying things like "Potion use was detected, data not collected."

It could potentially have a feature to exclude data from say, those with a 4-set bonus or a specific trinket to make comparisons more accurate.

Further additions could breakdown discrepancies between the user and the top performers for the spec.

I think this would be a great tool for DPS players to see where they stand in regard to their spec. Does such an addon exist currently?

The idea itself sounds good. Theoretically. In the real world it will end up in users cheating (and there's absolutely nothing you could do to pervent this). From that point all the data to compare with will be totaly worthless as you never could know if any given dataset is manipulated or not.

Item level has almost nothing to do with DPS output, stats on gear can be so different if you have 680 gear with bad stats for your class someone with the best stats for your class can beat you by 10k dps and more.
Try out Details! Damage Meter it has a modul for dps fights.
http://www.wowinterface.com/download...mageMeter.html