Dashboard Screen: Any way to customize with broadcasted messages, html, etc.?

I'm wondering, on the main Dashboard home screen, if there is a plugin where I can "broadcast" information from one location (such as my primary website's admin, etc.) and have it appear on my client's dashboard?

For example, let's say I install the plugin on Site A for the purpose of broadcasting to client's Site B... and I can add text, images, etc. in Site A's plugin and have it appear on Site B (and Site C, and Site D, etc.)?

I assume this can be done to some extent with RSS, though I've never done it myself.

Just looking for some direction. Thanks!