I see Samuel Huckins just had a post about apachetop http://dancingpenguinsoflight.com/2008/12/top-for-apache-activity/ which I have been meaning to mention for a while, but being that there is a fresh post about it I will mention Mytop instead.
Mytop is top for mysql. It can be used for monitoring the threads and overall performance of a MySQL.
Its an easy install in debain with a quick aptitude install mytop.
Here is some example output (sorry my mysql server isnt very busy atm).
