Presuming I have understood you correctly, I would do it like this:
Give your list an id, e.g.:
<li data-user="1">John Doe <span id="span-1"></span></li>
<li data-user="2">Jane Doe <span spanid="span-2"></span></li>
Then you can do this:
which allows you to iterate over all of the <li> elements in the list and call a function on each of them.
Within the function
$(this) will refer to the current element, so
$(this).atr("data-user") will give you the workers id, and something like
$(this).find(':first-child') will give you the correct <span> to stick the result in.
I hope that helps (and that I understood your question correctly :))