Good work Patrick. I'd point out another, tricky source of failure: crappy dns hosting. It's worth it to buy dedicated dns hosting from two different providers. The cost is about 50 bucks per year.
Still, thanks, I'll pencil that onto the "thing through when not 3 AM" list.
Using dual 3rd-party DNS does give you one very good advantage in acute situations, though. When your host goes down hard you can still repoint domains, receive email, etc.
In general I recommend dispersing services: put your company's blog on a subdomain hosted somewhere else like Weebly, and use something like Google Apps to handle your domain's email routing.
In case you're not familiar with it, a hidden primary configuration is just a master setup to allow zone transfers with the zones themselves not including a delegation to the master. This means the only queries your master serves are zone transfers requested by the secondaries.
whois archivd.com
Domain servers in listed order:
NS1.WORLDWIDEDNS.NET
DNS0.MTGSY.COM
NS2.WORLDWIDEDNS.NET
DNS1.NAME-S.NET
NS3.WORLDWIDEDNS.NET
DNS3.MTGSY.COM
been happy with it, and they have an easy to use API so if you are doing ~cloud~ things, you can script adding DNS entries etc quite easily from most programing languages.