APP For Team Texting in Widgets

I am a manager, we have 3 locations.
We need to improve communication with regards to inventory,
and we need to nail this down.
I am setting up an MK808 Android stick
and LCD screens on everyone desk,
at each location.

I hope someone can point me to an APP that will allow us to have a SIMPLE "text box" in the form of a widget (that can be resized), where information about: Inventory needs and reminders about Cleaning floors and and anything can be put into one device and seen on them all. (IE: A d "Dynamic text widget across multi platforms)

IE: Person "Posts" a Text that read reads: Dear people B,C, and : Please remember to Email Person A about your inventory needs this week. SO that A can order some for you.

I understand sending tests over phones, and emails are out there.
But I work for nonprofit and we are SOOO short on staff its not funny.
I plan to place the MK808's + LCD screen next to work computers,
so there is a dedicated device for communicating needs.

Sure, I could just send out a group text/ email, but that just adds work to my frantic day where I may only get seconds a DAY at my desk.... and if all I have to do is look to my right at the 2nd screen and see someone/everyone has posted their needs, or wants or that they have completed a task... It makes life easy for me and all of us.

I know twitter/others are out there, but we need it to be private and I need to be able to "sell" these ideas to a group of people who are EXTREMELY afraid about communications "leaks" becoming public even is they are simply inventory related. (we all have work place politics, I hope you understand)

If you dont know of such an app, other ideas are fine to mention, but my heart is set on what I've mentioned. But, any ideas are welcomed. I know this is a basic question, and Im sure there is MANY apps out there that do this sort of thing, but I work 80hrs a week at 2 jobs and so I dont have time to research them all. So if you know of anything like this or simple, please let me know.

I was thinking about a simple windows instant messenger, but I like the android platform. Tho, if anyone feels very strongly that, that is a WAY better way to go and is kind enough to say why, Im open to it.

Thank you.