I don't know how many of these are available but i think admin should look at this and should add these feature in future because we love wp buttons.
- Tweet button from twitter: Follow request after tweeting a post. Can be set in default or can change or add via template function. This will help adding the authors twitter account in the tweet button. (vary in post by post. So setting by function will help to change the username)
- Individual function for each button and also account info can be set by function argument. This will give flexibility to call them in theme template. Where we need only facebook or twitter we can add them just by calling them.
That's all for now. I will keep adding things if i have more idea.