"Pay It Forward", popularized in 2000 by Catherine Ryan Hyde with the release of her book of the same title, is a simple concept -- do something good for someone else and, if they ask to pay back the favor encourage them to extend the favor to someone new (pay it forward). This one action, repeated over and over, could have a monumental effect on your personal brand.
I always have a list in my head of people in transition and people looking for connections. Whenever I am talking with someone, either by phone or in person, I float the question, "Do you know of any companies that are looking for a ______ (fill in the blank)?" Most of the time the answer is "no", but one in ten or a hundred is still worth the effort.
This simple act of keeping others in mind -- extending the favor -- has been a boon to my personal brand. Even though I never ask for anything in return, and ask the favored person to pay it forward, I am still building a personal brand that returns to me tenfold.
The key to making this work is that you should never expect a favor to be returned. If you do it, AND, are keeping score you will never be content. But, if you do this service simply because it is the right thing to do, over time, you will feel incredibly blessed at your fortune -- and your personal brand will skyrocket.