"Any ideas on this? Reform the U.N. and hope it can finally take up the job? Restrict voting membership to non-totalitarian governments? Rework NATO or some other group into such a police force? Keep on going with individual nations making their own calls on these things, and keep away from any kind of World Government?"

Definitely keep away from a world government. The only time we will need a world government is when we need to respond interplanetary issues.
We don't need one, yet.
Generally speaking I disagree with your premise. I don't think the war against terrorism or war with Iraq has changed anything as far as world relationships. Rather I see, the Cold War as being an interruption and influence on world politics. The Cold War changed/warped the political fabric- covert wars were the only real option- a real war always had the possiblity of ending human culture. So I would say we are currently living in a world which is still suffering from the affects of the Cold War. Of course we still want to avoid any type of World War, and of course we still want to avoid any war. The ending of the Cold War, naturally, created a vacuum, and the Cold War has done damage. I think that if those idiots hadn't crashed into the World Trade Center, then US would have had to provide some direction at some point- though you could argue that it did in the form of Free Trade and/or what's called Globalism. I see the War of Terrorism, way of returning to more "normal relationship"- we are saying we are no longer going to tolerate covert wars which includes *allowing* political "expression" in the form of terrorism. 911 provided us an excuse to do the right thing- actively work towards bringing more peace to the world. But it doesn't mean we are going to take the job of the World Policemen. We still only act when it's in our national interest, and we still want to work with other countries, and we insist on following the Rule of Law and other countries do this also.
For instance, we don't generally want to get involved with other countries' civil wars- though we want to do all we can to create a climate which doesn't breed wars.