You can use them as coffee cup warmers by cutting of the bottom part and then when in need of a mug warmer slip over the hot beverage cup to insulate it and keep it warmer for longer amounts of time.
A Sweater for Small Pets
If you have a small dog or kitten you could use it for a pet sweater by cutting holes for arms and legs.
A Beanie for Baby
If there big enough and you have a little one you can cut of the top part and use the bottom part as a beanie.
I like using old socks for cleaning, saves on paper towels or when I have to clean somewhere where I really don't want to. You can also use socks to store small things in a closet. Just nail them on the wall.
You could cut the bottoms out of 2 or 3 of them, sew them together to make a tube. Stuff and sew both ends closed and you have a draft dodger to keep your house warm. Add a string to reach the door knob to hang it when not in use or keep in place.