The bbPress & WordPress User Defined Polls Plugin creates beautifully simple way for users to define their own polls for your bbPress forum postings and WordPress posts.
The screenshot below shows the “thumbs up” icon that the plugin inserts in to the forum posting controls. Click the icon to like the posting and hover over it to see who else has liked the posting. Only logged-in users can like posts. The icon is greyed (as shown) when the logged-in user has already liked the posting.