Is It Down Right Now? - Network & Admin
Hyperping - Cheap uptime and performance monitoring with detailed reporting and flexible alerting
Site Down - Site down outage and downtime reports from SiteDown.co
WebGazer - Monitor your website's availability with WebGazer, review its performance and get instant notifications when your website goes down. No installation required and free plan available.
Is it Down? - Is it down can check if a website is down or is it just your PC that can not access it.
Checkify - Super minimal, simple and inexpensive 24/7 uptime monitoring