Anyone who runs a website knows about the importance of tracking outages and catching them fast. There are plenty of website uptime monitoring services around that send you a text message or e-mail when your site goes down. SelkeyMoonbeam has shared an interesting project on Instructables, showing you how to build a website down alarm. It will ping your website every few seconds for trouble and alerts you.
When the light is off, your site is online. When it turns on and stays on, the website being monitored is down. There is also a special lighting pattern when there is a system error. You will need a Tessel, a relay module, and an alarm light to get stated.