From Zach Scrivena:
Nap pauses for a specified duration, and displays a countdown. Features varying levels of verbosity. Runs on any OS with the Java Runtime Environment (JRE 5.0+). Nap is free software written in Java and released under the GNU GPL license (version 2). Version 0.2 improved command-line interface; option for user to abort countdown; option to pause before exiting.