SolarWinds Pingdom - With website monitoring from Pingdom, you will be the first to know when your website is down. No installation required. 14-day free trial.
Rigor Monitoring & Optimization - Rigor Monitoring & Optimization is a website monitoring and performance measuring software solution that allows you to view the website from a customer perspective and conduct various tests to enhance the performance and working of the website.
Site24x7 - Site24x7 offers both free & paid website monitoring services. Monitor websites remotely and receive instant email/sms alerts if your website becomes unavailable. View uptime & performance graphs of your website monitors.
eG Enterprise - From application performance to user experience to infrastructure usage, get performance answers from a single console. Troubleshoot fast with actionable insights.
ScienceLogic - ScienceLogic simplifies data center, cloud, and network monitoring with its all-in-one platform.
WebSitePulse - WebSitePulse monitoring service. Test your site and server. Design your own monitoring service.