Pingbreak - Pingbreak is an original and free monitoring service.
cutestat - Website Stats and Valuation. CuteStat.
DownDetector - A simple service to tell you whether a website is down.
WebsiteOutlook - WebsiteOutlook is an all-in-one website that provides you detailed information on famous websites based on various data sources like traffic, page rank, and estimated ad revenue.
Silent Down - Silent Down is a website uptime and performance monitoring platform - Get notified instantly if your site is down or having performance issues.
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.