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.
WeShelter - Unlock a donation when you pass a homeless person in NYC
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
TAP London - Tackling the homeless problem together
Better Uptime - We call you when your website goes down
Catchafire - Use your professional skills to help charities