First of all - I am completely blown away with how amazingly fantastic Monit and M/Monit are. It has been a long time since I've found something that just *works*, works as advertised and does so straight out of the box.
One feature that I'd like to see is the ability to have conditional monitoring based on timeframes, e.g. between 0800 and 1700 local time, CPU load on given server is OK to be over 50% usage, but between 1700 and 0800, it should be below 25%.