If you understand it to be a temporary venture and plan for the next step, you can still use API's etc. and create unique web apps that will attract users and give you either publicity or short term revenue.
Also, I like to focus on businesses that, once I set my vision in place for satisfying customers, I can guarantee that the service will be there for my customers.
I am not looking for exposure, cash or partnerships -- those aren't the problem at all -- but I am looking for sustainable, trustworthy, long-term business ideas.
I have no problem building a business on another business' API's, but based on the track record of doing so, and your comments about them being temporary by nature, I think I will stay away from them.
I think we're in agreement there.