Powie's Uptime Robot Plugin
Uptime Robot (www.uptimerobot.com) Shortcode and Widget Plugin
Plugin Tag: server monitoring
Server Monitor
Adds three simple widgets to your WordPress Dashboard displaying fundamental info about your server and…
Gigaom New Relic
Configures New Relic to better track performance, errors, and uptime of WordPress sites, including multisite
Server Info WP
Easily monitor your server by watching your server usage and resources with three widgets.