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.
cutestat - Website Stats and Valuation. CuteStat.
UptimeRobot - Free Website Uptime Monitoring
Rankchart - Rankchart is one of the unique websites that allows you to examine your websites or watch competitors and locate rich information about website technologies, site reputation, errors, SEO, and ad-word recommendations.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Site Worth traffic - Site Worth traffic is a cost-effective site that is introduced to estimate the value, daily page views, daily visitors, and daily revenue of a website.