Add an extra button to the toolbar line

Hey,

I was wondering if anyone knows how I can add an extra “box” on this toolbar line:

[img]https://img297.imageshack.us/img297/4558/wordpress.jpg[/img]

Because there is this piece of code I add in every one of my posts on WordPress, so it would be good if I could click on one of them buttons and it will display it for me.

Thanks ??