RackTables - Racktables is a nifty and robust solution for datacenter and server room asset management.
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.
Racksmith - RackSmith is designed to provide an easy to use web interface to manage equipment and connections...
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Opendcim - a free, web based Data Center Infrastructure Management application.
Better Uptime - We call you when your website goes down