From Beau Blaser Software:
The Blaser Emergency Alert Messaging System is the premiere alert system for Windows computers in a network environment. When an alert is sent, all computers instantly display the full-screen alert message regardless to what the user is doing. The only requirement is that the computer is powered-on (and connected to the network). Runs as a system service- no one needs to be logged in. Send alert messages to thousands of computers in seconds. This version is the first release on CNET Download.com.