I've said it before, and I'll say it again. Allowing others to build on your own ideas, benefits everyone in the end.
Andrew Brown in today's Guardian has written a very similar critique on the ownership of ideas. Having an idea is one thing, having a good idea is a hundred times better, but exploiting your interpretation of that idea is the notion that needs to be protected, not the idea itself.
No two people will ever read something and have the same reaction to it, or an identical view of it. If you put your idea in the public domain, but make something useful or saleable out of it, then you have a right to ensure that no one duplicates the item that you have created from the idea. The idea itself, can be used to spawn other ideas, and that is best done by the power of collective intelligence, not a single owner.
So this writer advocates that only the concrete instance of an idea should be able to be protected by the law of copyright, not the idea itself. This is not to say that you should not necessarily profit from the use made by others of your intellectual property. If, in using your idea, someone uses your physical instance of it, or a copy, then you should be able to receive a fee, like a type of value-added tax.
People should be able to make money on the difference between their output ideas and their input ideas, just as a company is taxed on the difference between the value for which they sell an object and the value for which they bought the raw materials.
Ideas are the raw materials of the information age, so don't keep them to yourself - trade them.