I think it is very interesting how a person can go to a website and click and button, and BAM, they're mining for the website owner. I'm not against it. I think it's cool. It's an easy way for noobs to mine, even though they're using their CPU, and get paid.
But consider this: Would it be POSSIBLE for an individual to create a website, ANY WEBSITE, and have the website covertly slurp up some of the processing power of the visitor? Essentially, they could have the visitor mine for the website owner without their knowledge?
Now, I'm not passing judgment here. I think it would be very interesting. Imagine a day where all(or a lot of) website owners rig their website to slurp up processing power of every visitor. It would be a super easy way to make your website generate revenue. Forget donations. Forget ads. Imagine where you, the visitor, go to all sorts of websites throughout the month and you're funding the websites without any effort. You just have a higher electricity bill every month.