In order to make your blog social you can use the following plugins for proper voting features letting users reveal their opinion and/or for managing polls you post on a WP blog.
Post Star Rating
Post Star Rating is a plugin so solid as minimal. Although its compatibility with WP 2.9 is not covered, there are all the features and (in hindsight) are not based on anything particularly unstable to be of concern.
Once activated, the plugin can be included where needed …