One of the key drivers behind Cloud Computing, of course is the standardization of web API's around the REST programming model. Whether you are a Technology provider, Content provider or Service provider there is always room for a strategy to monetize or deepen customer relationships, foster a stronger community via REST API's. So, based on your target market, chances are you can always unearth Business models that can monetize your API's with appropriate Billing, API usage provisioning capabilities.
Lets look at a few examples:
1. NetFlix: By opening up the API's to their movie titles and subscriber queue's, they enable richer user experiences outside of the Netflix web site context (e.g. I'm sure there are iPhone apps for Netflix in the works), Enables new partners and generally all sorts of niche players (e.g. Online Bond movie communities building apps around their interests). Its all about moving "down" the Long Tail, and get a communities to build stuff that NetFlix can't do alone. Its all about faster innovation, driving more "positive" feedback in to their user base.
2. BestBuy: is all about getting their catalog/estore to wherever you hang out on the web. Talk about extending your customer reach...literally, extending your sales channels.
3.Shopping.com: again, is all about growing the eco-system of customers, partners by enabling off-site experiences.
Exposing API's, Metering the usage of the infrastructure supporting the API's, catering to the "Long Tail" via enabling crowd-sourcing...all of these facilitate new business models or extend existing business models in a highly leveraged manner. You're literally extending the reach of your business development activities, and with appropriate tracking/measurements in place (e.g. what part of your API use cases are popular, growing like crazy etc) you have a mechanism to weed out and surface viable business models or extensions to current business models.
Of course, it takes a lot of discipline and focus to manage these changes (e.g. watch out for cannibalizing existing channels or incentive structures etc). Corporations, however big, can't think of all the great ideas themselves, it just makes sense to enable communities, accept the wisdom of "crowd sourcing". After all, isn't this the age of the programmable web?