Be more green and train yourself to save energy by not leaving the computer idle.
When the computer spends more than 10 minutes idle, the blue button changes to a red button with a small text showing the number minutes without any use.
After a sign of activity the notification stays for 10 seconds and the button returns to its original blue state.
If you leave the computer running and return a few minutes later, the icon will tell you how many minutes of energy were wasted, making you feel filthy and guilty... hopefully encouraging you to sleep the computer the next time, and the next time, until it becomes a habit.
Note: Chrome stopped supporting the technology that allowed the extension to suspend or send the computer to sleep mode directly from the browser, so that feature won't be available from now on (Sep. 2014).
Other works
http://imagentleman.github.io
Extore is a team of professionals who are passionate about creating extensions for web browsers. This devotion also gives us opportunity to appreciate work of other people. We get inspired by useful, open source extensions made by developers all over the world. Our strong belief is that one should share helpful add-ons with others. That’s why we’d like to present you our ever-growing list of favourite extensions that have inspired us. Moreover, as you probably have already learned, sometimes struggling for the best brings an end to the good. Talking about add-ons it often turns out that an upgrade is worse then previous version. Also it can become really tricky to get back to the beloved version of your favourite extension. That’s why we’re going to make not only the latest, but all versions of our favourite (and we hope yours too) add-ons available for download. No more compromises, just stick to the version you really like!