Tweetcount Widget Retweet Button
The BackType Tweetcount widget lets publishers display the number of tweets their posts get on Twitter, and lets readers easily retweet
TweetMeme Button
The Retweet button is for website and blog publishers that want to encourage their audience to retweet their content on twitter.
Easy Retweet Button
The script itself is completely standalone (no dependencies) and can be included in any page relatively painlessly. Additionally, since it's just HTML, CSS, and JavaScript, it's completely themeable ...