I just knit my first pair of sock for Warm Woolies. Check out their site for details, but they provide knitted garments for orphans overseas and for poor children on two reservations in South Dakota.
They ask that items be knit either in bulky weight or double-stranded worsted weight. I chose the latter for these socks, and I think it gave it a cheerful color scheme. Items should also be mostly or all wool since it does so well in cold wet weather.
If you have some extra time or yarn on your hands, what better way to use both up? This is a great cause, but you can always find something else if you like. Just google "charity knitting" and you'll find plenty to keep you busy.