Help the elderly, visit the lonely, feed the hungry. Maybe it's because I'm in my midlife crisis, but as I think how much time I put into hobbies I wonder how much good I could have done in the same time. But creating music, build scale models, growing cactuses, watching movies is a lot of fun. And people need time to relax and enjoy life.
My family makes a point to look after others in the church we're part of, generally by inviting them over for dinner and/or by bringing gifts of food.
Music-making and cooking are two hobbies that share really well, but you can do just about anything together.