This reminds me of "This Little Light of Mine" - the song that if you start singing among a group of singers, you will have a full harmony gospel song on your hands in no time. :) This works with any group of singers, 'cause harmonies are so easy to come up with for it, it lends itself to the counter-melodies and makes everyone's heart a little lighter. It's a great way to break the ice when you're with a new group. But what's always interesting with this song is being reminded ahead of time - what the song means. And then let your voice be one of the lights that shines in the reflected glory of God. The harmonies that can be created are utter joy to the ear.
Going back to salt, I figure this can actually be linked with capacity fairly well. If we are to flavor life, to make it attractive to others, we need to realize that not everyone is attracted to the same flavors - some enjoy spice, others sweet; some are as we would describe "salt of the earth" and others as "salty" and still others "old salt". Each of us have personalities that attract different types of people. And for people to feel comfortable, they have to know that their particular personality or flavor or salt will be welcome among the family of God - if only appreciated by a few. :)
What are your favorite ways of being that City on the Hill? How do you flavor your interactions with others? What ways do you use to reflect God's light in your own life to attract others to journey to God?