This add-on reminds you when a website comes back online.
What it does
Every 5 minutes, send a request to the website and if it's back online send you a notification.
The icon is from GLYPHICONS.com, released under Creative Commons Attribution 3.0 Unported (CC BY 3.0). Support them by visiting their website.
If you would like to support the creator of this extension, feel free to donate.