RE:
https://www.mediawiki.org/wiki/Extension:AJAXPoll
Today, I published a new version of the AJAXPoll extension.
Most important change:
poll results are only shown for users who have voted.
Can be configured (deactivated) per-wiki, and also per-poll (see manual).
A database schema change is needed: run php update.php .
Have fun with it.