What causes are you most passionate?
Find a non-profit in your city or town supporting a cause in which you really care about and volunteer with them for 1-2 hours a week. If that's too much, how about earmarking a few hours just one day a month?
If time really is something you just can't give, then how about "going the extra mile" and writing the organization a support check to help keep doing what they're doing? If you care about a special cause, don't assume someone else will make it happen.
YOU are that someone else.
Make a difference.