I don't know how many people give to charities at Christmas time, but my favorite one to donate to is Samaritan's Purse. The program they have going right now is called Operation Christmas Child. To support it, you pack stuff that kids need and may not be able to get into a shoebox and they'll ship it somewhere it's needed. Stuff you can pack in includes soap, washcloths, toothpaste, toothbrushes, and socks - so in short, basic things you need in everyday life. One idea a friend of mine had is to include a pillowcase, which can help sanitation.
One of these simple shoeboxes can change a child's life.