System Configuration and Management — Produce and deliver reports on system utilization (processor, memory, disk, and network)

sar appears to be the tool to save the day here. Installed and running by default, the sysstat package contains tools that capture system performance throughout the day, and automatically summarizes it for you. Generating utilization reports is then a simple matter of knowing the right sar command to execute. If all else fails, simply try man sar

• Processor
• Basic processor report: sar or sar -u
• Basic report every second for the next 10 seconds: sar 1 10
• Load average: sar -q
• Per processor statistics: sar -P ALL
• Power management (not enabled by default): sar -m
• Memory
• Kernel paging: sar -B
• Unused memory: sar -r
• Swap space: sar -S
• Disk
• Disk IO stats (avg): sar -b
• Disk IO stats: sar -d (-p to use pretty names)
• Network
• Network statistics: sar -n DEV
• Network errors: sar -n EDEV
• Everything
• All reports simultaneously: sar -A

Links with more information:
http://www.linux.com/archive/feed/52570
http://www.softpanorama.org/Admin/Monitoring/sar.shtml