I tested some Chaval heated gloves a while back, and found them to be excellent. My review:
http://www.gearinstitute.com/skiing/ski-gloves/item/chaval-response-xrt-electrically-heated-gloves
Finally chiming in.@SkiNurse and @Tricia have tested the Thermic IC1300 PowerGloves -- in fact, a review is coming out shortly. The verdict was two (toasty) thumbs up. I think @SkiNurse has tried some other heated mittens but they didn't really work for some reason. Maybe she can chime in.