I donate every couple months to the Vietnam Veterans of America. They are great; you schedule a pick up and when they are in my area they come and pick everything up. I have about 3-4 bags accumulating right now, I'll have to make the call again soon!
I was thanked for my "blessing" (not my donation) when I dropped off a trash bag of clothes and random household items today. I always thought when I donated something that someone MIGHT find what I donated useful but I never thought about the possibility that someone may be wishing for exactly what I was donating, and receiving it might feel like a blessing.