The flame malware stuxnet is based on has turned up in several places and is a good place to start. So is the equation group leaks. Those are the two major sources known for info on US/Isreal/five eyes countries. Another interesting thing to look up is the "black rooms" in global datacentres. China and Russia have their own "state" malware as well that goes by various names. Not to leave off North Korea, they do a lot of cyber warfare themselves and have a university apparently dedicated to it.

Basically every major world power has their own secretive hacking groups, malware, and pool of zero day exploits. Hilariously, the best way to find out what your country has got is to look it up from an anti-virus vendor based in another country.

Kaspersky Labs in particular (might be connected to Russian govt but interesting anyways) is a great source to learn about state sanctioned malware besides Russian/Chinese stuff.