That green button also exist for your own use. ShareThis is a plugin for Internet Explorer that adds that green button to your taskbar so you can automatically send links and news you want to share for any reason.
ShareThis is compatible with the most famous online services: del.icio.us, Twitter, Facebook, Technorati, Meneame, Digg..., and it allows you to share the links in two different ways.
You can share them via e-mail or via online services, that's really good because some of your frinds don't use internet services like del.icio.us or digg and you want them to view the link you are suggesting.
This is ShareTHis for Internet Explorer, you can find Firefox version here.