The always-excellent Slacktivist has a long but very readable post about the evils of big monopolies. Go read it.
I continue to maintain that any Libertarian whingeing about "big government" fails to take into consideration the fact that, in theory at least, the government is accountable to the people, while international corporations (and especially monopolies) can and will do anything that they can get away with. It is only the government that is capable of defining what they can get away with. The government may not presently be as accountable as it should be, but that is the fault of the voters. So, when the opportunity arises, vote, and vote responsibly. Only that way will we get both fair government and fair businesses.