Searching the net for info on long lost friends, I found a link to a site that provides an RSS feed of which stars are within a light cone starting with your birth (assuming you were born on earth).

Occurred to me that since this is how much of the Universe could possibly have heard the news of your birth, and given the Universe is thought to be at least 92 billion light years across, one can cube ones age in years, divide by the cube of 92 billion, and you have a rough figure giving an upper limit for what proportion of the Universe (by volume) could have heard of you or been affected by your actions.

Okay the calculator on my computer shows it as something like 10^-30, or in a more human friendly format, it gives the answer as "0". Perhaps I should multiply by 100 to make it a percentage ;)