Admin Message provides an easy way to show short messages to users via the creation of Admin Message nodes which are displayed in a block. The messages can be individually closed by users (both logged in and anonymous via a cookie).
Examples could be "Welcome to this site...", "Temporary downtime...", "Important security announcement...", "New feature...", etc.
By default, messages that were created before a user registered will not be shown to that user. This can be overridden by the "Always show this message" option. Also, a PHP visibility option, similar to the "Pages" display option used for blocks, is available for each message. Those experienced with PHP may use this visibility option to only show a message for users of a specific role, show a message if a user has not filled in a profile field, etc.
The version for Drupal 5 is still available but is now unsupported. Sorry for the inconvenience!
Work on a Drupal 7 version has began but is still at a very early stage:
This module was initially developed by and for Demoex.net.