The concept of a World Government has long been entirely in the realm of science-fiction, but as these organizations show, it is now very possible. The biggest obstacle has always been communication and coordination, and with the high-speed, world-wide satellite systems available today, it is possible to organize across the planet with little effort. This is good for Interpol, as it helps with law enforcement, but it also causes problems like Financial Contagion, where a minor problem becomes a major one simply because of fast communication.
One of the few things that hasn't been covered is that all of them are also incredibly complex bureaucracies given their international make up and jurisdiction. Given that any one country has laws and customs and rules about how to conduct any of the things they govern including trade, criminal proceedings, trials, etc., these organizations attempt to bring all that together and create binding international agreements. This can be incredibly tricky and then is also often ignored by individual states depending on what they feel is appropriate or what is necessary to remain in the club.
What is interesting about these bodies is the way that they function transnationally, or deliberately work outside of the borders of any one country. For these bodies to exist it is important that they work in this way as their existence depends on globalisation. They in some respects, therefore, represent a challenge to nation-state sovereignty.
As previous answers have suggested, each of these organizations has been a major player in the process of "globalization." They are deliberately international organizations, designed to promote greater cooperation between and among nations. Whether globalization is a good or bad thing depends very much on one's views about nation states and national sovereignty.
The WTO and the US Council for International Business are both advocates of free trade, the World Bank provides the capital for developing countries to undertake projects that in turn become interesting to foreign investors, and Interpol has increasingly taken a role in dealing with "white collar" crime across borders in addition to the high-profile terrorist cases they also have to deal with. Each of these organizations has been instrumental in "globalization" after WWII, and many, especially the World Bank and the WTO, were dominated by modernization theorists who thought that democracy would inevitably follow economic development.
All of them are committed to the idea of internationalism. These are all organizations that want to promote cooperation and trade between various countries. Liberals (in terms of the theories of International Relations) like this sort of organization. They believe that more cooperation between countries leads to less conflict.