Certificate CA pinning

With many MITM attacks, you get fake certs.  CA pinning would help to fix this: The browser would retain a copy of every cert that it gets in a local DB and if it gets a different cert next time you visit the same domain or if the signing CA is different, it gives you a warning.  Carry on at your peril.   This kind of attack is mainly the state sponsored threat actor: they have the resources and the clout to persuade a CA operator to sign a bogus cert and\or onsert themselves in DNS traffic.
Ok, so since writing this article, I have discovered Certificate Patrol Firefox plugin, which does exactly what I described above.  Just like all most great ideas - someone has had it already!  If you use firefox, go grab the plugin.