Dave's idea is a good one. There are some things that could be done fairly easily. One example of which is the lack of an underline markup code. Why this was left out I'll never understand. Other things like the ability to quote someone with the click of a button may take a little more effort, but could still be done fairly easily.
I'm not sure how you would develop the list of features to include in a poll, but perhaps you can look for those that have the most response? There have been quite a few suggestions made in the Feature Request forum on the UBBThreads Support Forums. That may be a good place to start...