I've been asked by several people where I donate my hats. This year I gave them to Warm for Winter. A little checking in your own area through your LYSs, guilds or community services groups should turn up places to donate to people in need in your own community.
Here was this year's final pile.
I didn't even count how many hats were there. Let's just say it was an awful lot plus some scarves, cowls and one pair of mittens!