For ads there's adblock. No problems with contributing to a collective mining effort, I just want to be asked.

I was looking for an alternative payment method for online shops after the wikileaks disaster. Bitcoin isn't there yet. Running jsMiner *without* giving visitors a chance to opt-in is putting people off. It is simply stealing resources. It's kind of a gold rush, right? Try to control your greed. People got so used to ads and all the tracking crap that no one questions those methods any more. Treat your community / potential users with respect and you will have unlimited support. Otherwise the whole idea will end up like e-gold and die off eventually.