RegScanner - Free utility that allows you to scan/search the Registry, find the desired Registry values that match to the specified search criteria, and display them in one list.
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.
Windows Registry Recovery - Windows Registry Recovery is the perfect tool for MS Windows that enables you to recover data from crashed machine registries with great ease.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Registry Workshop - Registry Workshop is an advanced registry editor.
Better Uptime - We call you when your website goes down