What do you think of microtransactions, virtual goods, and “freemium” products?

I wrote an article about this a bit ago. I think it's a really interesting phenomenon, and so far it's been surprisingly successful. But only when something like that is completely integrated and easy to do will it work for everyone. So there's no telling when someone will figure out a system by which microtransactions can be as easy and thoughtless as buying something with a credit card is at any given store in real life.