I agree about the electric paint mixer. I've had the "no name" brand from Micromark for a couple of years now ($10), it does a better, faster job of mixing than toothpicks, sprue, or any hand held variety of stick, and like previously mentioned, it is so efficient you can resurrect old paint that could never be brought back by hand stirring. The other great advantage is that it wastes less paint, by far. When you use sticks a relatively large amount of paint is left on the stick, which gets costly after a time if you use good quality paints and mix small amounts (which is common). The more surface area on the stick, the more paint you lose (McDonald's coffee mixers vs toothpicks, for instance) With the electric mixer, when I finish mixing the paint, I raise it just slighly above the surface of the paint in the bottle and let the mixer run for a couple of seconds. The centrifugal force of the spinning action removes most of the paint and it ends up back in the bottle. Given the cost of a bottle of Tamiya or Gunze acrylic, which is what I use most often, my electric mixer has paid for itself a couple times over by now. It's also nice to finish mixing paint in less than a minute, rather than five--- unless you get some perverse pleasure out of (literally) going through the motions.
TomB