As you can see, they got 2 buttons..
A Tall(big) button
next, replace [twitter_name] with your Twitter username.
and [post_url] with your page URL.
And a Wide(small) button
Advantages of Topsy Retweet ButtonTopsy is a Real time search and discovery engine that was launched in last May. and unlike TweetMeme retweet button. Topsy holds the data about tweets of your link forever!
Topsy offers free tweet analytics about your link & your site that currently TweetMeme will charge you for it! [ See analytics of my popular Twitter Friends widget]
It also shows any badges earned for your URL in TopLinks.(TOP 100, TOP 1k, TOP 5K ). TopLinks are collections of the top 100, 1000, and 5000 new links tweeted each day by influential people on Twitter.