Privacy Manager for Zeitgeist is a graphical user interface which lets you easily control what gets logged by Zeitgeist. It supports setting up blacklists according to several criteria (such as application or file types), temporarily stopping all logging, and deleting recent events.
Screen Message displays a given multi-line message as large as possible, fullscreen and black on white. You can specify the text when launching sm, or edit it while the program is running. It is useful to send messages across a room (e.g., during a university lecture). For fast startup, it is recommended that you bind it to a key in your Desktop Environment.
notification-thing is a full-featured implementation of the Desktop Notifications Specification. It is not tied to any specific desktop environment, and is focused on features like rate-limiting and flexible filtering to minimize distraction and noise ratio in a transparent way, without silently dropping anything ever.