Re: invert display colors b->w, w->b
Such functionality belongs in a composition manager like compiz or kde4's kwm. At least kde4 supports it and I guess compiz too.
Note that depending on your type of display this won't save you any power. E.g. in case of an LCD screen the backlight is always on and the 'crystals' just make sure not all light passes through the screen. In case of a CRT monitor it would save a little as black means that the tube is off.
Personally I would find a different way to save power e.g. running the cpu and gpu at lower clocks.