It's a very light Redhat Linux and Oracle OVM System Performance Monitoring tool written in Perl using rrdtool for Database and Graphing. Allows you to query the RRD database given a set of dates and generates a web based graphs. Easy to install. Uses less disk space than most performance monitoring tool. Data of each host monitored is kept for 2 years and occupy less that 25 MB of disk space.
jLlama is a desktop application to monitor servers over SSH. Any figure retrieved from the command line can be polled and graphed in real time. Out of the box, jLlama can graph CPU and Memory usage for Linux and Solaris servers.