There are parameters (options) for three retweet buttons counters: Tweetmeme, Backtype and Topsy. You can get more control over your tweet buttons with options listed for those three tweet counters.
Find answers how to:
- change the @username who is tweeted
- change the size of the button
- what to do when the URL is different from the current URL
If you are interested in implementing twitter button on blogspot check Add twitter retweet button to blogger.