I think in time we'll see communities based on membership where you do pay a fee, and then if you behave badly you'll get nuked and kicked out of the community. And it needn't be limited to one site. You could have a site goodcitizen.com and then people would have accounts with it, and their membership there would allow them to participate in blogs, etc.

The trick will be in who finds a good way to do the 'justice' system right. I've thought about this model quite a bit..

Another problem is payment systems. Part of the culture of the internet with payments is that you have to work with parties who have a business model based on bad faith. Google checkout seems to be changing that though, and now is the first time I've thought about the model since evaluating them.