:last-child Selector
Selects all elements that are the last child of their parent.
.last-child()
While .last() matches only a single element, :last-child can match more than one: one for each parent.
Find the last span in each matched div and add some css plus a hover state.
JS
<div>
  <span>John,</span>
  <span>Karl,</span>
  <span>Brandon,</span>
  <span>Sam</span>
</div>
<div>
  <span>Glen,</span>
  <span>Tane,</span>
  <span>Ralph,</span>
  <span>David</span>
</div>
CSS
span.solast {
  text-decoration: line-through;
}
HTML
$("div span:last-child")
  .css({ color: "red", fontSize: "80%" })
  .hover(
    function () {
      $(this).addClass("solast");
    },
    function () {
      $(this).removeClass("solast");
    }
  );
DEMO