What are the most unnecessary things governments do, sponsor and spend money on.   

A case in point:

From http://www.salon.com/opinion/greenwald/2009/11/16/terrorism/index.html?source=newsletter:

The British journalist Johann Hari has written an absolutely vital article for The Independent, examining a growing movement of former hardened Islamic militants who are now devoted to teaching a more moderate and less fundamentalist Islam.  Hari focuses on understanding what motivates some Muslims to turn to radicalism and terrorism in the first place, and how that process can be reversed.  Though these ex-militants have very diverse backgrounds, they all stress two critical facts:  (1) the more the foreign policy of the West is seen as aggressive, violent and oppressive to the Muslim world, the easier it is to convert Muslims to violent radicalism, and (2) the most potent weapon for undermining Islamic extremism is the efforts of Westerners to work against their own governments' belligerent policies. ...

In other words, the very policies the U.S. has been pursuing in the name of combating Terrorism -- invading, occupying, and bombing Muslim countries; locking them up without trials; torturing them; violating the values we've been preaching to the world -- have been the most potent instruments for fueling Islamic radicalism and terrorism.  By contrast, those who have been continuously accused of being "soft on Terrorism" and even being allied with the Terrorists -- those who opposes our various wars, who demanded and provided basic human rights protections and equal liberties to Muslims, who objected to their own governments' oppressive and belligerent policies -- have done more to diffuse and impede Muslim radicalism than virtually anyone else in the world. ...

But warmongers won't quit coz they have powerful sponsors all over the place:

I put , among other things, research on drugs and space flights. Of course, I meant research on unnecessary drugs, such as spending millions of dollars, on some arthritis drug, which has more side effects than advantages, in the end. I also put excessive space flights, I should have specified it this way, not all space flights, more like one every three weeks. 

I put wars of course and cloning, the most ridiculous thing, one might invent, in my opinion.    

Wars.

Other: where should I start?

The most unnecessary thing governments do is proliferating.

Some of the other things to be opted for (like war) are not unnecessary, they are criminal.

- experiments with creation of the Universe

- experiments with fertilization and birth

- genetic engineering

I do not know if governments do these thing, but people do, harmfully to the laws of creation.   

As one of those fortunate taxpayers who footed the bill for the exhibition of Jana Sterbak's Vanitas: Flesh Dress for an Albino Anorectic, I have to put "Art" at the top of the list.

One of the other most unnecessary things any government does is protecting citizens from themselves. That`s just unnecessary. Not letting the citizens to protect/defend themselves is criminal.