ZPacks has these: http://www.zpacks.com/accessories/carabiner.shtml
Weight: .1 oz / 2.8 grams
Length: 1 5/8", Width: 1", Thickness: 1/8"
Material: Anodized aluminum
At exactly one tenth of an ounce these are the smallest and lightest carabiners around. They are perfect for clipping items to your pack, hanging your food bag, and many other uses.
They are strong enough for almost any backpacking application, but are not meant to support a human's weight.