XS seems to work for most 6 to 10 year olds. they're still too big for Joyanna, who wears size 5T clothes, but she'll be in them next summer when her other "children's" gloves are too small.
My hand is about average for a woman, I think, and I take an Atlas Medium. The Small fits too -- goes on, but is uncomfortably tight after a while. Likewise, the Large fits me with just a little extra room at the fingertips and a little extra play around the palm & knuckles. You get the idea -- these are pretty stretchy!
How long do you think you'll have this sale open? I was thinking I could see if anybody else wanted to order with me and pick up their gloves at the Mid-Atlantic spring swap...