Mr Uptime
Mr Uptime 0.9.2 for Windows
Sam Nurmi Browser & Email / Browser Tweak
Firefox extension that notifies you when an unavailable website starts to work again

Software Summary:

You can run Mr Uptime on Windows operating systems. Mr Uptime is a software product developed by Sam Nurmi and it is listed in the Browser & Email category under Browser Tweak. Mr Uptime is a free software product and it is fully functional for an unlimited time although there may be other versions of this software product.

Alternatives in Browser & Email on Windows