Indicator Applets seem to be like buses: you spend ages waiting for one, and then a dozen turn up all at once.
Indicator-Syspeek is a system-monitor applet for Ubuntu, capable of displaying CPU, RAM, Disk and Network usage.
Developed by Georg Schmidl, the indicator icon load changes with every 10% increment of CPU load. When the CPU is maxed out (100%) it turns blood-red — handy! ;)
Download
Syspeek is available for Ubuntu 11.04 users only, and can be installed via a .deb package (here) or installed from its official PPA @ ‘ppa:vicox/syspeek’.