Pretty common sense but most people don't use 3d models. Advantages are you can see your opponents gear while targeting him line of sight. Its usually win or lose going for the right person in arena, and you would want to go for the weakest link.
ZMDB old version, works with 2.4, new version has animations but its best to have static models.
Zuxana's Model Citizen&ZMobDB Advanced - Interface Additions - World of Warcraft Mods, Addons, and More!
Here is the new version
WoWInterface Downloads : Unit Mods : ZMobDB Advanced5
Also to fill up proximo quickly when arena starts (reminder)
Make a macro with
/tar a
/tar b
..............
.......
/tar z
and spam just as the arena is about to start. Have fun !