Another thing to try for reducing power consumption is to use a "dark" color scheme and solid black background instead of fancy wallpapers that "light up" lots of pixels. No idea how much it can save, but should have some benefit.
Sorry, not a bit of savings there. These screens are backlit, and the color of the pixel has no real effect on power. They simply let varying amounts of the backlight through. Not using animated screensavers will make a difference, however.