An egg timer over the internet.
Perhaps egg timer is not the right name for it. Off<>zz timer would be better! Off<>zz is a laptop and piano duo experimenting with electro-acoustic music via improvisation. Their performances show a diverse range of computer sounds in combination with improvised piano music.
Interested? Have a look at the work of @narcode, or take a look at the Off<>zz [youtube channel] (https://www.youtube.com/channel/UCJCFCrJFEm1yLS9itcUNjuQ) or [SoundCloud] (https://soundcloud.com/offzz).
The webtimer runs a clock on the server. Users can visit a webpage to see the current countdown, the next interval for the countdown clock and the next next interval for the clock.
Users can interact with the countdown. They can change the next interval durations up or down by 10 seconds (but not more than 120 seconds and no less than 20 seconds). Users can also leave a comment or suggestion to the performers. Once the timer runs out, the screen starts flashing and it loads the new timer interval. All the users share the same countdown clock and comments, so it becomes an entire interactive performance experience.
There are a couple of special commands (links) to reset the timer, to clear the user comments, or to set a special set of intervals. The special set can be a series of 120, 110, 100, ..., 10 seconds, or a number of the same interval time. When the series ends, no new intervals are added anymore and the timer ends with a red screen (until you start a new set of intervals or reset the clock).
The WebTimer is a JAVA web application. You can tell maven to 'package' the project and it generates a war-file (or alternatively you can pick any war from the release directory).
Upload this war file to your JAVA application server (like tomcat) and visit the application url.
Enjoy!