Folder Marker - Change folder color in two mouse clicks for easy at-a-glance identification.
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.
Folder Painter - Folder Painter is an easy to use Portable Freeware program, which allows you to change the color of the icon representing a chosen folder to any color you like
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Dr. Folder - Customize windows folder
Better Uptime - We call you when your website goes down