Dark Eldar have the ability to launch quite a devastating Alpha Strike if used correctly. I haven't decided on the complete list just yet, but I'm building it around Absdrubal Vect and The Baron. Given the high point total of Vect, this would probably only be utilized in 2000+ point games, but what these two characters provide is a +1 to go first roll, and a 4+ Seize the Initiative. In other words, the odds are weighted heavily in your favor.
The major downside of this HQ combo is that Wracks are out as Troops. But since the focus of the army is firepower, they will probably be replaced by 5-man Warrior squads toting Blasters.
Get the first turn, shoot your opponent up, and have some assault support elements to be in his face by turn 2.