Amazon EC2 and 'Pay As You Go Applications'
Just in case you never heard of Amazon EC2, go here first.
Right now, they charge you for the time the server is up and the consumed bandwidth. They provide 'Pay As You Go Hosting'.
I think Amazon is quite close to enable 'Pay As You Go Applications' if they support some kind of revenue-sharing model.
For example, suppose I built a web-based CRM application, and I'm selling it through my website. My customer pays me $5.000, he downloads the application, install it in his server and run it.
What if my customer can host it in Amazon EC2 and instead of charging him 0.10 per hour / 0.20 per GB they charge him 0.15/hour 0.25/GB and pay me 0.05/hour and 0.05/GB? The customer, instead of paying me $5.000 for my CRM, he'll pay depending on how much he uses it.
Now we have 'Pay As You Go Applications'. I think it opens a new world of interesting business models.