Just Uptime is a server monitoring service that monitors your website/server from 3 location worldwide. When an issue arrises, JustUptime alerts the user via there mobile using SMS.
Users have permenant access to their logs which can be used to generate flash graphs displaying there uptime and response time over a given period.
Just Uptime can perform a variety of checks including HTTP/HTTPS, Ping, TCP/UDP, DNS and POP3/IMAP/SMTP every 1-60 minutes. Everything is done through an online control panel and there is no software or scripts to install.