votes – The unofficial WordPress Plugin Directory

Upvote / Downvote – Vote with a Tweet

Allows users to vote on a topic using Twitter. Display results in standard banner sizes on posts, pages or widget. Optional Adsense Revenue Share.

Add AJAX poll to your WordPress blog. You can use our polls on sidebars, posts and pages.

Allows logged users to vote up or down to topics and replies inside bbPress, just like you can on StackOverflow for example.