I've been writing postcards here secure.everyaction.com/wWYzSycvi0uy.... They send you postcards for free, but you'll need to buy the stamps.
I've also done postcards through Field Team 6: www.fieldteam6.org/postcarding1. With Field Team 6 you'll need to buy the postcards and stamps.
My greatest source of hope right is hearing that. I never got involved beyond voting before this year, and i've heard from so many others saying the same thing.
Happy 4th!