I was wondering if anyone knew of an addon that could do any of these things.

1. Show a frame with all previously targeted/attacked enemies within combat and show the buffs/debuffs on them.

     //optional: show a frame with all enemy npc's currently attacking/targeting you or your pet

2. Provide click targeting support within a frame, so targets could be switched more easily than trying to tab through a cycle, or clicking the NPC.

     //this would be used for finding a particular mob within a group that has the same name as the other mobs.

The primary use of this addon would be to have the ability to find targets that you have yet to attack, and as a result, have no DOT's on them or whatever.

I imagine it to look similar to a party frame, except for enemies.

I'm looking for the same thing... having trouble targetting the new add that spawns in the Emalon encounter as a tank.

Not possible, sorry :) If I can give you an advice: use an assist macro if you are DPS and use raidtargetframes if you are a tank. A tooltip indicating wich raidmembers are targetting that mob might be also usefull.

Actually such an addon is possible. Granted it would take work. However in truth it is possible. It would have to use a set of checks to clear dead or out of range enemy units. As well as update enemy units also within current range. Plus more.