I knit for our local, keeping kids warm chapter.
It was set up for kids (up to 23 years old) that are homeless for various reasons, to ensure while they are out in the cold they have hats, scarves, mitts etc.
I also knit for our local hospitals nicu, as my daughter was born with a lung problem and one of the greatest things I remember about the time in there, was how the nurses used to dress her in the cutest little hats and booties to keep her warm and cozy. I only took one hat home and left the others for the next babies coming in. I also encourage my daughter (who is now 11) to knit for charity also. We try to live by the one for us, one for donation strategy.
We keep a small rubber maid container in our home that we put all the finished items in until we have enough to take with us to the destination.
Another one I support is the Dulaan project.
No matter how small every little bit is appreciated.