Is there an option that I'm missing that would add a column that displays the username of the last person to post to that topic? If not, any hacks?

That should be showing on your board automatically I believe. Do you mean like how Infopop's UBB here shows the last post on the forum summary page?

If you mean in the list of topics within a forum, then no that is not a standard feature of UBB. You can try checking over at http://www.ubbdev.com to see if there is such a code mod.

If so, please post a direct URL to your UBB and tell us what version of UBB6 you're using for further information.