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.
NetVizura NetFlow Analyzer - NetFlow Analyzer is a solution for bandwidth monitoring and traffic analysis. It helps with traffic investigation, analysis and reporting
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Zabbix - Track, record, alert and visualize performance and availability of IT resources
Better Uptime - We call you when your website goes down
Nfsen - NfSen is a graphical web based front end for the nfdump netflow tools that allows you to: