I think my biggest learnings from building systems, and although he didn't mention it explicitely, he did mention it, is to build your system to self heal.<p>Shit happens, whether it is a database starting to fall over for some reason, or your heap growing too big, or who knows what, something will eventually fail.  Having monitoring to tell you that is of course the first step, but the second is to have that monitoring be able to shoot everything in the head to see if it fixes things.  It doesn't always work, but does a lot of times, and although inelegant will usually result in a better user experience.<p>Every system needs to be able to self heal, especially if you want to keep your sanity and you are a small outfit.