There are many organizations that assist members of our military, police, firefighting, and other services. I'd like to focus on a somewhat less visible group—the working and service dogs that do so much for us, both in dangerous missions and search & rescue, and in assistance for the deaf, the blind, and many others.
Not only do these dogs face dangers we can't explain to them and bond loyally to their handlers, but it can be difficult to ensure that they are properly protected at the end of their working careers. The organizations here help support them, and even provide homes for dogs that are trained but not suitable for the life of a service dog.
Many a retired dog has given a veteran a new lease on life. Look here for articles about adopting and living with a service dog.