Desktop Earth - You should run it as admin.
Pingdom - With website monitoring from Pingdom you will be the first to know when your website is down. No installation required. 30-day free trial.
TerraTime - TerraTime provides an amazing, interactive, real-time virtual Earth.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Xplanet - Xplanet is free software, distributed according to the terms of the GNU General Public License.
Better Uptime - We call you when your website goes down