We write about allot of tools that are geared towards windows system on this blog.   I do from time to time deal with a Linux server.  This weekend I found a tool that is a must have for all Linux administrators.  The tool is collectl and was created by Mark Seger over at HP.  Mark actually used it to monitor large clusters, but also noticed it could be used by the average Linux administrator on an everyday basis.  Collectl replaces sar, vmstat, top, atop, iostate, and allot of other tools that are currently out there.  This tool does it all.  The tool is also a sourceforge project and is being constantly updated.

Sourceforge Page
http://collectl.sourceforge.net/