Customize Dashboard Main Screen

So I know there is a feed plugin that lets you add feeds, as well as one for hiding the wordpress feeds. I seem to remember there being a way to customize the rest, but I can’t find it. I want to have a special welcome message and instructions for all my users across the whole network. I’m not particularly attached to the current dashboard widgets. It sure would be great if there was a network dashboard widget area somewhere. Then we could easily change it… but for now I’d settle for a plugin that lets me customize it. Any thoughts?

Thanks as always!