Comment by troels

Production Error Tracking

Concur. It is an immensely useful tool, simple as it may be to set up. There are services that do it for you (getexceptional), but it literally takes only a few hours to throw your own together.

Issue tracking is probably moving too much into management territory for this list, which is why I think they left it out.

It's probably for the same reasons that they don't touch upon server management/configuration, but I have personally found puppet (or other similar tool) very useful. It's basically source control for your server configuration - once you start using it, it seems reckless to not have.