watch command is a great way to quickly monitor the status of something.
Imagine a file being transferred to your server and you want to know when its done. .... watch -n 1 ls -l <file>

This is a quick way to view your CPUs current speed.
all command go inside "" and then you can pipe away.

Anyway below are come cool quickies. Alias them for quick acces up to you.

Quick view CPU speeds
watch -n 1 "cat /proc/cpuinfo | grep -e 'cpu MHz'"
cpu MHz		: 800.109
cpu MHz		: 800.149
cpu MHz		: 800.018
.....
Quick view system memory state
watch -n 1 "cat /proc/meminfo | grep Mem"
MemTotal:       16247104 kB
MemFree:         8763996 kB
MemAvailable:   11186060 kB