Here's some things that could be improved upon.
1. Firstly, hide the poll when posting a new thread. It's adding a lot of unneeded clutter. This has been suggested before here: http://xenforo.com/community/threads/hide-post-a-poll.6785/
2. Allow polls to have more than 1 question.
3. Add a setting to each poll to either "Treat all questions as one question" or not, could be a tickbox. What this means is that if you haven't ticked "Allow selection of multiple responses" and haven't ticked "Treat all questions as one question", you will be able to select 1 response PER question. Having 4 questions would mean that you can select 4 responses(1 from each question). If you have ticked "Treat all questions as one question" and haven't ticked "Allow selection of multiple responses" you'll only be able to select 1 response for that whole poll, regardless of how many questions there are.
This could be useful when conducting a poll on 2 different usergroups. Like question 1; "If you're a member, do you find the searchbar confusing?" Responses; "Yes", "No", "What searchbar?". Question 2; "If you're a moderator, do you find the moderation tools easy to use?" Responses; "Yes", "No", "Well, I know how to ban someone..". There are of course endless amounts of uses for this.
However, you'll only be able to ask 1 question to each usergroup with that system, that's where suggestion #4 comes in.
4. Allow several polls in the same thread. This would effectively take care of the problem that occured in #3. Each poll is treated on its own. You could - following the example from #3 - set up 2 polls, each poll having not ticked "Allow selection of multiple responses" and having not ticked "Treat all questions as one question". That way you can set up multiple questions on each poll and the users can vote for only 1 response per question.
5. Then there's also Brogan's excellent suggestion regarding an easier way to input large amounts of responses. Original thread here: http://xenforo.com/community/thread...-to-be-entered-into-a-single-text-field.7326/
I know there's more suggestions out there regarding polls but here's at least some that I wish to highlight.