LOL, this is a very old thread but here is a good enough answer that works.
How we do it:
Only mods, supermods and admins can start polls at our message board. Normal posters can request a poll and if it is reasonable a moderator will make it for them.
If there is a normal thread that would work better as a poll, a staff member will start a new poll and then MERGE it into the original thread. The poll pops up to the top. The post that was associated with the poll thread is buried chronologically in the big thread, so you have to delete that post and edit the first post of the original thread if you want to explain the poll.
Messy but it works.