Is there a tool that when you post a bulletin if someone clicks on it they will then send it out to thier friends also?
yes - it would be called a virus. A myspace virus. In time people would undoubtedly start writing bulletins about it, to warn other users.
It would be hard to make as well: it would involve hacking in myspace itself to activate javascript as the link to the bulletin is being clicked.
There was a tool for this a while back, which has since been blocked by myspace. By completely disabling java, they have blocked a lot of these "virus" type tools. So I don't think you will have much luck in your search for this bulletin virus...i mean...tool.