Unions give a voice (Score 1)

Why is there such animosity toward unions? Yes, they can be corrupt, but as with your government that is the fault of largely apathetic constituency. The one crucial benefit to a union is that it offers the majority of those working in and who presumably have interests in a corporation some voice at the decision-making levels.

In a small hi-tech company, say 100 people or less, the situation of the lowest employee is not so greatly removed from that of the CEO. In much larger corporations, say Oracle, there is a much greater divide between the coders in India and Larry Ellison in his japanese mansion. No, the union should not be about giving every indian worker their own equally lavish mansion, but it should be about putting a voice with enough weight (presumably representing a majority of the company's workforce) into the decision making process which often neglects employees in favor of board member bonuses, etc.

In short, I think it is the extreme separation between masses of employees and their employers that makes unions important as a means of bridging that gap. Alternatively, or in conjunction with stock options one could ideally transform an employee into someone with a greater commitment and conception of the company. (=better employee)