GraphMyWebsite (www.graphmywebsite.com) is a free website monitoring service provided by the good people here at Squidworks.
This service monitors websites for outages and graphs their performance. If your looking for a easy website uptime monitor and alerting service GMW is for you. Get email notifications when failing services are detected.
GMW provides all services for free and there is no catch. Just enjoy the tools. They also do IP GeoLocation tracking, DNS Slueth along with an array of other network test. Go give them a try.