Assuming you are using ShapeShifter and a nice modern GuiKit dark theme like NEOS, Shinobi or JetBlack, the OSX Menubar icons (Volume, Battery, Clock, Displays, etc) should change to an appropriate colour, usually the same colour as the menu text.
So I assume you mean third party menu extras such as the Konfabulator gears. Things like this can be changed pretty easily. All you need is a copy of photoshop. The icon is usually a .tif file inside the "Resources" folder of the application's package. All you need to do is find it, open it up in photoshop and change it to whatever colour you like.