I realize this is a suggestion that has probably already been made for Omen or Recount or the like, but is there an AddOn that records the data from Omen (Threat-1.0, KTM, etc), and can put it into a graph for a selected individual? A quick google search revealed http://forums.worldofwarcraft.com/thread.html?topicId=1778578625&sid=1 and I cant help but wonder if the data is already there, how difficult would it be to log it as a part of Recount or Omen?
Not very. I wrote that script; I haven't updated it for the Devastate changes because it would be slightly more difficult than simply changing values and I'm lazy. Using Threat-1.0 as a source of threat numbers would be very smart. However, I'm not a Lua programmer and did I mention the lazy bit?
The right approach would be a small addon that consumes Threat-1.0 data and logs via the SavedVariables file; add to that a script/program that consumes that file and produces a threat graph. Not too hard.
Recount does graph the threat. You select threat as the display value on the main panel. You then add to current chart. If you check integrate it will show total threat at each time in the fight. Once the graph is displayed you can add other party members. It's good for showing why someone pulled aggro, i.e. did they out-threat you or start too soon.
Personally, it's of limited value and until 2.4 there isn't much way for such a chart to be of much value. It shows threat on your current target. As an example with Moroes he vanishs every 30s so it shows your threat dropping to zero every 30s then rising rapid back up when he reappears. Since threat is by mob name when you start the second or third target by the same name it shows you with significant threat when you have none.
That said it is useful for showing the relationship between your threat and that of other players, particularly if your dpsers are threat capped. I like to promote the idea of threat utilization, i.e. how much of the threat generated by the tank was actually used by the dpsers. The graph, when integrated, gives a good feel for threat utilization. It would be a bit more helpful if you could normalize everyone to the tanks threat. Still though if you are peaking significantly higher than your dpsers then the threat utilization is low and generating more threat is not the answer to any aggro problems you may be having.