Is there a command in CentOS4 or some small program to display a short message everywhere possible on a box much like # shutdown -k now "Display me where I'll be seen", but without the added (normal) stuff? xmessage would probably be usable if it had an -onalldesktops option.
BTW, the purpose is to add a visual to the scripts I have in place to remind me to connect my external USB drive late Tuesday, disconnect it early Wednesday (after backup) and keep it out of the reach of "Murphy" for the rest of the week.