Games Workshop has posted a new hobby article looking at some sample 40K Dark Eldar armies.
From their website:
A race that has practiced its acts of unremitting evil for more than ten thousand years, the Dark Eldar are at the pinnacle of their style of warfare. With scores of unusual and arcane weapons at their disposal they are more than capable of matching not only their incredible dexterity and agility against the best in the galaxy, but also their deadly tools of destruction.
In this article we look at three sample Dark Eldar armies: a force centred around the Dark Eldar Kabals, a Wych Cult and finally a combined force, representing the tenuous alliances that lead to devastating realspace raids.