Ganglia is a monitoring system that uses RRDTool for its storage and graphs. This provides an excellent solution for monitoring, but suffers from data becoming less detailed ("averaged out") when you look further back in time. This is deliberate, but does make later analysis of the data difficult.
If you wanted to keep detailed records of monitoring data with MonAMI that don't degrade over time, now you can, I've committed changes to the mysql plugin in CVS. In addition to monitoring a MySQL database, the plugin can now store information. You tell it which table and how to map the information into that table and it does the rest, it'll even create the table if it doesn't exist.