A modified Obsidian Coast made to be a dark version of Aqua (a mac osx like theme). I basicaly changed the background color and kept the blue things. There is also an emerald theme (made from the Aqua one) and a QtCurve theme (also made from Aqua). Finaly I use Tibanna as Plasma Theme as it uses KDE color scheme.

Emerald Theme : http://kde-look.org/content/show.php/Aqua+Dark?content=158520
QtCurve Theme : http://kde-look.org/content/show.php?content=158521

Oh and just for fun : the hexa code for the background color is #424242.