Fine article from Cory Doctorow on positive externalities and how things like DRM arise out of resentment of people gaining value from the incidental side-effects of things you have done. I particularly like:

"You translate a document because you need it in two languages. I come along and use those translations to teach a computer something about context. You tell me I owe you a slice of all the revenue my software generates. That's just crazy. It's like saying that someone who figures out how to recycle the rubbish you set out at the kerb should give you a piece of their earnings."